The directors present the strategic report for the year ended 31 December 2024.

The group provides engineering and consultancy services to sectors including construction, design, defence, security and oil & gas.

The group recorded a profit before tax of £649,978 (2023: £1,154,351). The directors consider this to be the key measure of the group's trading performance. The increase in profit before tax is mainly due to reallocation of corporate expenditure across the region during the year.

While our security and government business remains strong, oil and gas revenues remain weak and strategic initiatives are in place to counter this with greater focus on decarbonisation and alternative energy.

Operational risk

Operational risk is the risk of loss due to inadequate or failed internal processes, people, systems or from external events. The group manages operational risk by having suitable processes and systems in place. Our risk management function looks to capture risk information in a robust and consistent manner.

Legal and reputational risk

In the ordinary course of business, these risks could lead to reputational damage or legal censure, fines or prosecutions and other types of non-budgeted operational risk losses associated with our conduct and activities. The group has no appetite for material risk levels which may result in such outcomes. We maintain a robust and appropriate internal control environment and this is regularly reviewed and analysed.

Cyber risk

Risks exist that are associated with digital technologies, devices and media. Cyber risk is never a matter purely for the IT team, although they clearly play a vital role. An organisation's risk management function needs a thorough understanding of the constantly evolving risks as well as the practical tools and techniques available to address them.

Financial risk

Financial risk includes credit risk, liquidity risk, interest rate risk and foreign exchange risk.

Economic risk

Economic risk includes wider economic downturn resulting in the further decline of oil and gas and a fall in government expenditure would have a significant impact on the Group. This is is mitigated by our diversification into other customer bases and the field of decarbonisation and alternative energy.

Credit risk

Credit risk is the risk that a counterparty will be unable to pay amounts in full when due. Key areas where the company is exposed to credit risk are amounts due from clients. The group manages the levels of credit risk it accepts and such risks are subject to regular review. Each account is closely monitored by the credit control function.

Liquidity risk

Liquidity risk is the risk that cash may not be available to pay obligations when due. The primary liquidity risk of the group is the obligation to pay third parties including suppliers. Regular forecasts are performed to ensure that the group maintains an appropriate level of liquidity.

Foreign Exchange Risk

Foreign exchange risk is the risk that the group may be exposed to fluctuations in exchange rates between GBP other currencies.

On behalf of the board

The directors present their annual report and financial statements for the year ended 31 December 2024.

The principal activity of the group continued to be that of engineering and consulting, and for the company it continued to be that of group holding company.

The results for the year are set out on page 9.

No ordinary dividends were paid. The directors do not recommend payment of a further dividend.

The directors who held office during the year and up to the date of signature of the financial statements were as follows:

Saffery have expressed their willingness to remain in office as auditors of the group.

The directors are responsible for preparing the Annual Report and the financial statements in accordance with applicable law and regulations.

Company law requires the directors to prepare financial statements for each financial year. Under that law the directors have elected to prepare the financial statements in accordance with United Kingdom Generally Accepted Accounting Practice (United Kingdom Accounting Standards and applicable law).

Under company law the directors must not approve the financial statements unless they are satisfied that they give a true and fair view of the state of affairs of the group and company, and of the profit or loss of the group for that period. In preparing these financial statements, the directors are required to:

• select suitable accounting policies and then apply them consistently;

• make judgements and accounting estimates that are reasonable and prudent;

• state whether applicable UK Accounting Standards have been followed, subject to any material departures disclosed and explained in the ;

• prepare the on the going concern basis unless it is inappropriate to presume that the group and company will continue in business.

The directors are responsible for keeping adequate accounting records that are sufficient to show and explain the group’s and company’s transactions and disclose with reasonable accuracy at any time the financial position of the group and company and enable them to ensure that the financial statements comply with the Companies Act 2006. They are also responsible for safeguarding the assets of the group and company and hence for taking reasonable steps for the prevention and detection of fraud and other irregularities.

So far as each person who was a director at the date of approving this report is aware, there is no relevant audit information of which the auditor of the company is unaware. Additionally, the directors individually have taken all the necessary steps that they ought to have taken as directors in order to make themselves aware of all relevant audit information and to establish that the auditor of the company is aware of that information.

This report has been prepared in accordance with the provisions applicable to companies entitled to the medium-sized companies exemption.

We have audited the financial statements of Thornton Tomasetti Holdings UK Limited (the 'parent company') and its subsidiaries (the 'group') for the year ended 31 December 2024 which comprise the group statement of comprehensive income, the group statement of financial position, the company statement of financial position, the group statement of changes in equity, the company statement of changes in equity, the group statement of cash flows and notes to the financial statements, including significant accounting policies. The financial reporting framework that has been applied in their preparation is applicable law and United Kingdom Accounting Standards, including Financial Reporting Standard 102 The Financial Reporting Standard applicable in the UK and Republic of Ireland (United Kingdom Generally Accepted Accounting Practice).

In our opinion the financial statements:

• give a true and fair view of the state of the group and of the parent company's affairs as at 31 December 2024 and of the group's profit for the year then ended;

• have been properly prepared in accordance with United Kingdom Generally Accepted Accounting Practice; and

• have been prepared in accordance with the requirements of the Companies Act 2006.

Basis for opinion

We conducted our audit in accordance with International Standards on Auditing (UK) (ISAs (UK)) and applicable law. Our responsibilities under those standards are further described in the Auditor's responsibilities for the audit of the financial statements section of our report. We are independent of the group and parent company in accordance with the ethical requirements that are relevant to our audit of the financial statements in the UK, including the FRC’s Ethical Standard, and we have fulfilled our other ethical responsibilities in accordance with these requirements. We believe that the audit evidence we have obtained is sufficient and appropriate to provide a basis for our opinion.

Conclusions relating to going concern

In auditing the financial statements, we have concluded that the directors' use of the going concern basis of accounting in the preparation of the financial statements is appropriate.

Based on the work we have performed, we have not identified any material uncertainties relating to events or conditions that, individually or collectively, may cast significant doubt on the group's and parent company’s ability to continue as a going concern for a period of at least twelve months from when the financial statements are authorised for issue.

Our responsibilities and the responsibilities of the directors with respect to going concern are described in the relevant sections of this report.

Other information

The directors are responsible for the other information. The other information comprises the information included in the annual report other than the financial statements and our auditor's report thereon. Our opinion on the financial statements does not cover the other information and, except to the extent otherwise explicitly stated in our report, we do not express any form of assurance conclusion thereon.

Our responsibility is to read the other information and, in doing so, consider whether the other information is materially inconsistent with the financial statements or our knowledge obtained in the course of the audit, or otherwise appears to be materially misstated. If we identify such material inconsistencies or apparent material misstatements, we are required to determine whether this gives rise to a material misstatement in the financial statements themselves. If, based on the work we have performed, we conclude that there is a material misstatement of this other information, we are required to report that fact.

We have nothing to report in this regard.

Opinions on other matters prescribed by the Companies Act 2006

In our opinion, based on the work undertaken in the course of the audit:

• the information given in the strategic report and the directors' report for the financial year for which the financial statements are prepared is consistent with the financial statements; and

• the strategic report and the directors' report have been prepared in accordance with applicable legal requirements.

In the light of the knowledge and understanding of the group and the parent company and their environment obtained in the course of the audit, we have not identified material misstatements in the strategic report or the directors' report.

We have nothing to report in respect of the following matters in relation to which the Companies Act 2006 requires us to report to you if, in our opinion:

• adequate accounting records have not been kept by the parent company, or returns adequate for our audit have not been received from branches not visited by us; or

• the parent company financial statements are not in agreement with the accounting records and returns; or

• certain disclosures of directors' remuneration specified by law are not made; or

• we have not received all the information and explanations we require for our audit.

As explained more fully in the directors' responsibilities statement, the directors are responsible for the preparation of the financial statements and for being satisfied that they give a true and fair view, and for such internal control as the directors determine is necessary to enable the preparation of financial statements that are free from material misstatement, whether due to fraud or error. In preparing the financial statements, the directors are responsible for assessing the parent company's ability to continue as a going concern, disclosing, as applicable, matters related to going concern and using the going concern basis of accounting unless the directors either intend to liquidate the parent company or to cease operations, or have no realistic alternative but to do so.

Our objectives are to obtain reasonable assurance about whether the financial statements as a whole are free from material misstatement, whether due to fraud or error, and to issue an auditor's report that includes our opinion. Reasonable assurance is a high level of assurance but is not a guarantee that an audit conducted in accordance with ISAs (UK) will always detect a material misstatement when it exists. Misstatements can arise from fraud or error and are considered material if, individually or in the aggregate, they could reasonably be expected to influence the economic decisions of users taken on the basis of these financial statements.

Irregularities, including fraud, are instances of non-compliance with laws and regulations. We design procedures in line with our responsibilities, outlined above, to detect material misstatements in respect of irregularities, including fraud. The specific procedures for this engagement and the extent to which these are capable of detecting irregularities, including fraud are detailed below.

Identifying and assessing risks related to irregularities:

We assessed the susceptibility of the group and parent company’s financial statements to material misstatement and how fraud might occur, including through discussions with the directors, discussions within our audit team planning meeting, updating our record of internal controls and ensuring these controls operated as intended. We evaluated possible incentives and opportunities for fraudulent manipulation of the financial statements. We identified laws and regulations that are of significance in the context of the group and parent company by discussions with directors and by updating our understanding of the sector in which the group and parent company operates.

Laws and regulations of direct significance in the context of the group and parent company include The Companies Act 2006 and UK Tax legislation.

Audit response to risks identified

We considered the extent of compliance with these laws and regulations as part of our audit procedures on the related financial statement items including a review of group and parent company financial statement disclosures. We reviewed the parent company's records of breaches of laws and regulations, minutes of meetings and correspondence with relevant authorities to identify potential material misstatements arising. We discussed the parent company's policies and procedures for compliance with laws and regulations with members of management responsible for compliance.

During the planning meeting with the audit team, the engagement partner drew attention to the key areas which might involve non-compliance with laws and regulations or fraud. We enquired of management whether they were aware of any instances of non-compliance with laws and regulations or knowledge of any actual, suspected or alleged fraud. We addressed the risk of fraud through management override of controls by testing the appropriateness of journal entries and identifying any significant transactions that were unusual or outside the normal course of business. We assessed whether judgements made in making accounting estimates gave rise to a possible indication of management bias. At the completion stage of the audit, the engagement partner’s review included ensuring that the team had approached their work with appropriate professional scepticism and thus the capacity to identify non-compliance with laws and regulations and fraud.

As group auditors, our assessment of matters relating to non-compliance with laws or regulations and fraud differed at group and component level according to their particular circumstances. Our communications included a request to identify instances of non-compliance with laws and regulations and fraud that could give rise to a material misstatement of the group financial statements in addition to our risk assessment.

There are inherent limitations in the audit procedures described above and the further removed non-compliance with laws and regulations is from the events and transactions reflected in the financial statements, the less likely we would become aware of it. Also, the risk of not detecting a material misstatement due to fraud is higher than the risk of not detecting one resulting from error, as fraud may involve deliberate concealment by, for example, forgery or intentional misrepresentations, or through collusion.

A further description of our responsibilities is available on the Financial Reporting Council’s website at: https://www.frc.org.uk/auditorsresponsibilities. This description forms part of our auditor's report.

Use of our report

This report is made solely to the parent company's members, as a body, in accordance with Chapter 3 of Part 16 of the Companies Act 2006. Our audit work has been undertaken so that we might state to the parent company's members those matters we are required to state to them in an auditors report and for no other purpose. To the fullest extent permitted by law, we do not accept or assume responsibility to anyone other than the parent company and the parent company's members as a body, for our audit work, for this report, or for the opinions we have formed.

These financial statements have been prepared in accordance with the provisions relating to medium-sized groups.

As permitted by s408 Companies Act 2006, the company has not presented its own profit and loss account and related notes. The company’s loss for the year was £15,310 (2023 - £11,329 loss).

These financial statements have been prepared in accordance with the provisions applicable to companies subject to the small companies regime.

Thornton Tomasetti Holdings UK Limited (“the company”) is a private company limited by shares incorporated in England and Wales. The registered office is 2nd Floor, 12-16 Clerkenwell Road, London, EC1M 5PQ.

The group consists of Thornton Tomasetti Holdings UK Limited and all of its subsidiaries, being Thornton Tomasetti Warrington Limited and Thornton Tomasetti Romsey Limited.

These financial statements have been prepared in accordance with FRS 102 “The Financial Reporting Standard applicable in the UK and Republic of Ireland” (“FRS 102”) and the requirements of the Companies Act 2006.

The financial statements are prepared in sterling, which is the functional currency of the company. Monetary amounts in these financial statements are rounded to the nearest £.

The financial statements have been prepared under the historical cost convention, modified to include certain financial instruments at fair value. The principal accounting policies adopted are set out below.

In the parent company financial statements, the cost of a business combination is the fair value at the acquisition date of the assets given, equity instruments issued and liabilities incurred or assumed, plus costs directly attributable to the business combination. The excess of the cost of a business combination over the fair value of the identifiable assets, liabilities and contingent liabilities acquired is recognised as goodwill. The cost of the combination includes the estimated amount of contingent consideration that is probable and can be measured reliably, and is adjusted for changes in contingent consideration after the acquisition date. Provisional fair values recognised for business combinations in previous periods are adjusted retrospectively for final fair values determined in the 12 months following the acquisition date. Investments in subsidiaries, joint ventures and associates are accounted for at cost less impairment.

The consolidated group financial statements consist of the financial statements of the parent company Thornton Tomasetti Holdings UK Limited together with all entities controlled by the parent company (its subsidiaries) and the group’s share of its interests in joint ventures and associates.

All financial statements are made up to 31 December 2024. Where necessary, adjustments are made to the financial statements of subsidiaries to bring the accounting policies used into line with those used by other members of the group.

All intra-group transactions, balances and unrealised gains on transactions between group companies are eliminated on consolidation. Unrealised losses are also eliminated unless the transaction provides evidence of an impairment of the asset transferred.

Subsidiaries are consolidated in the group’s financial statements from the date that control commences until the date that control ceases.

The financial statements are prepared on a going concern basis. The directors have taken into

consideration forecasts produced that take into account the impact of the current economic climate on both the company and the sectors it operates in. The conclusion of the directors is that they still have a reasonable expectation the company will continue in operational existence for the foreseeable future.

Turnover is recognised at the fair value of the consideration received or receivable for goods and services provided in the normal course of business, and is shown net of VAT and discounts.

Turnover from contracts for the provision of professional services is recognised by reference to the stage of completion when the stage of completion, costs incurred and costs to complete can be estimated reliably. The stage of completion is calculated by comparing costs incurred, mainly in relation to contractual hourly staff rates and materials, as a proportion of total costs. Where the outcome cannot be estimated reliably, revenue is recognised only to the extent of the expenses recognised that it is probable will be recovered.

Goodwill arising on the acquisition of subsidiary undertakings represents the excess of the fair value of the consideration over the fair value of the identifiable assets and liabilities acquired. It is initially recognised as an asset at cost and is subsequently measured at cost less accumulated amortisation and accumulated impairment losses. Goodwill is considered to have a finite useful life and is amortised on a systematic basis over its expected life, which is 10 years.

For the purposes of impairment testing, goodwill is allocated to the cash-generating units expected to benefit from the acquisition. Cash-generating units to which goodwill has been allocated are tested for impairment at least annually, or more frequently when there is an indication that the unit may be impaired. If the recoverable amount of the cash-generating unit is less than the carrying amount of the unit, the impairment loss is allocated first to reduce the carrying amount of any goodwill allocated to the unit and then to the other assets of the unit pro-rata on the basis of the carrying amount of each asset in the unit.

Intangible assets acquired separately from a business are recognised at cost and are subsequently measured at cost less accumulated amortisation and accumulated impairment losses.

Intangible assets acquired on business combinations are recognised separately from goodwill at the acquisition date where it is probable that the expected future economic benefits that are attributable to the asset will flow to the entity and the fair value of the asset can be measured reliably; the intangible asset arises from contractual or other legal rights; and the intangible asset is separable from the entity.

Amortisation is recognised so as to write off the cost or valuation of assets less their residual values over their useful lives on the following bases:

Tangible fixed assets are initially measured at cost and subsequently measured at cost or valuation, net of depreciation and any impairment losses.

Depreciation is recognised so as to write off the cost or valuation of assets less their residual values over their useful lives on the following bases:

The gain or loss arising on the disposal of an asset is determined as the difference between the sale proceeds and the carrying value of the asset, and is recognised in the income statement.

In the parent company financial statements, investments in subsidiaries, associates and jointly controlled entities are initially measured at cost and subsequently measured at cost less any accumulated impairment losses.

A subsidiary is an entity controlled by the group. Control is the power to govern the financial and operating policies of the entity so as to obtain benefits from its activities.

At each reporting period end date, the group reviews the carrying amounts of its tangible and intangible assets to determine whether there is any indication that those assets have suffered an impairment loss. If any such indication exists, the recoverable amount of the asset is estimated in order to determine the extent of the impairment loss (if any). Where it is not possible to estimate the recoverable amount of an individual asset, the company estimates the recoverable amount of the cash-generating unit to which the asset belongs.

The carrying amount of the investments accounted for using the equity method is tested for impairment as a single asset. Any goodwill included in the carrying amount of the investment is not tested separately for impairment.

Recoverable amount is the higher of fair value less costs to sell and value in use. In assessing value in use, the estimated future cash flows are discounted to their present value using a pre-tax discount rate that reflects current market assessments of the time value of money and the risks specific to the asset for which the estimates of future cash flows have not been adjusted.

If the recoverable amount of an asset (or cash-generating unit) is estimated to be less than its carrying amount, the carrying amount of the asset (or cash-generating unit) is reduced to its recoverable amount. An impairment loss is recognised immediately in profit or loss, unless the relevant asset is carried at a revalued amount, in which case the impairment loss is treated as a revaluation decrease.

Recognised impairment losses are reversed if, and only if, the reasons for the impairment loss have ceased to apply. Where an impairment loss subsequently reverses, the carrying amount of the asset (or cash-generating unit) is increased to the revised estimate of its recoverable amount, but so that the increased carrying amount does not exceed the carrying amount that would have been determined had no impairment loss been recognised for the asset (or cash-generating unit) in prior years. A reversal of an impairment loss is recognised immediately in profit or loss, unless the relevant asset is carried at a revalued amount, in which case the reversal of the impairment loss is treated as a revaluation increase.

Cash and cash equivalents are basic financial assets and include cash in hand, deposits held at call with banks, other short-term liquid investments with original maturities of three months or less, and bank overdrafts. Bank overdrafts are shown within borrowings in current liabilities.

The group has elected to apply the provisions of Section 11 ‘Basic Financial Instruments’ and Section 12 ‘Other Financial Instruments Issues’ of FRS 102 to all of its financial instruments.

Financial instruments are recognised in the group's statement of financial position when the group becomes party to the contractual provisions of the instrument.

Financial assets and liabilities are offset and the net amounts presented in the financial statements when there is a legally enforceable right to set off the recognised amounts and there is an intention to settle on a net basis or to realise the asset and settle the liability simultaneously.

Basic financial assets, which include debtors, are initially measured at transaction price including transaction costs and are subsequently carried at amortised cost using the effective interest method unless the arrangement constitutes a financing transaction, where the transaction is measured at the present value of the future receipts discounted at a market rate of interest. Financial assets classified as receivable within one year are not amortised.

Other financial assets, including investments in equity instruments which are not subsidiaries, associates or joint ventures, are initially measured at fair value, which is normally the transaction price. Such assets are subsequently carried at fair value and the changes in fair value are recognised in profit or loss, except that investments in equity instruments that are not publicly traded and whose fair values cannot be measured reliably are measured at cost less impairment.

Financial assets, other than those held at fair value through profit and loss, are assessed for indicators of impairment at each reporting end date.

Financial assets are impaired where there is objective evidence that, as a result of one or more events that occurred after the initial recognition of the financial asset, the estimated future cash flows have been affected. If an asset is impaired, the impairment loss is the difference between the carrying amount and the present value of the estimated cash flows discounted at the asset’s original effective interest rate. The impairment loss is recognised in profit or loss.

If there is a decrease in the impairment loss arising from an event occurring after the impairment was recognised, the impairment is reversed. The reversal is such that the current carrying amount does not exceed what the carrying amount would have been, had the impairment not previously been recognised. The impairment reversal is recognised in profit or loss.

Financial assets are derecognised only when the contractual rights to the cash flows from the asset expire or are settled, or when the group transfers the financial asset and substantially all the risks and rewards of ownership to another entity, or if some significant risks and rewards of ownership are retained but control of the asset has transferred to another party that is able to sell the asset in its entirety to an unrelated third party.

Financial liabilities and equity instruments are classified according to the substance of the contractual arrangements entered into. An equity instrument is any contract that evidences a residual interest in the assets of the group after deducting all of its liabilities.

Basic financial liabilities, including creditors, bank loans, loans from fellow group companies and preference shares that are classified as debt, are initially recognised at transaction price unless the arrangement constitutes a financing transaction, where the debt instrument is measured at the present value of the future payments discounted at a market rate of interest. Financial liabilities classified as payable within one year are not amortised.

Debt instruments are subsequently carried at amortised cost, using the effective interest rate method.

Trade creditors are obligations to pay for goods or services that have been acquired in the ordinary course of business from suppliers. Amounts payable are classified as current liabilities if payment is due within one year or less. If not, they are presented as non-current liabilities. Trade creditors are recognised initially at transaction price and subsequently measured at amortised cost using the effective interest method.

Derivatives, including interest rate swaps and forward foreign exchange contracts, are not basic financial instruments. Derivatives are initially recognised at fair value on the date a derivative contract is entered into and are subsequently re-measured at their fair value. Changes in the fair value of derivatives are recognised in profit or loss in finance costs or finance income as appropriate, unless hedge accounting is applied and the hedge is a cash flow hedge.

Debt instruments may be designated as being measured at fair value through profit or loss to eliminate or reduce an accounting mismatch or if the instruments are measured and their performance evaluated on a fair value basis in accordance with a documented risk management or investment strategy.

Financial liabilities are derecognised when the group's contractual obligations expire or are discharged or cancelled.

Equity instruments issued by the group are recorded at the proceeds received, net of transaction costs. Dividends payable on equity instruments are recognised as liabilities once they are no longer at the discretion of the group.

The tax expense represents the sum of the tax currently payable and deferred tax.

The tax currently payable is based on taxable profit for the year. Taxable profit differs from net profit as reported in the income statement because it excludes items of income or expense that are taxable or deductible in other years and it further excludes items that are never taxable or deductible. The group’s liability for current tax is calculated using tax rates that have been enacted or substantively enacted by the reporting end date.

Deferred tax liabilities are generally recognised for all timing differences and deferred tax assets are recognised to the extent that it is probable that they will be recovered against the reversal of deferred tax liabilities or other future taxable profits. Such assets and liabilities are not recognised if the timing difference arises from goodwill or from the initial recognition of other assets and liabilities in a transaction that affects neither the tax profit nor the accounting profit.

The carrying amount of deferred tax assets is reviewed at each reporting end date and reduced to the extent that it is no longer probable that sufficient taxable profits will be available to allow all or part of the asset to be recovered. Deferred tax is calculated at the tax rates that are expected to apply in the period when the liability is settled or the asset is realised. Where items recognised in other comprehensive income or equity are chargeable to or deductible for tax purposes, the resulting current or deferred tax expense or income is presented in the same component of comprehensive income or equity as the transaction or other event that resulted in the tax expense or income. Deferred tax assets and liabilities are offset when the company has a legally enforceable right to offset current tax assets and liabilities and the deferred tax assets and liabilities relate to taxes levied by the same tax authority.

The costs of short-term employee benefits are recognised as a liability and an expense, unless those costs are required to be recognised as part of the cost of stock or fixed assets.

The cost of any unused holiday entitlement is recognised in the period in which the employee’s services are received.

Termination benefits are recognised immediately as an expense when the company is demonstrably committed to terminate the employment of an employee or to provide termination benefits.

Payments to defined contribution retirement benefit schemes are charged as an expense as they fall due.

Leases are classified as finance leases whenever the terms of the lease transfer substantially all the risks and rewards of ownership to the lessees. All other leases are classified as operating leases.

Assets held under finance leases are recognised as assets at the lower of the assets fair value at the date of inception and the present value of the minimum lease payments. The related liability is included in the statement of financial position as a finance lease obligation. Lease payments are treated as consisting of capital and interest elements. The interest is charged to profit or loss so as to produce a constant periodic rate of interest on the remaining balance of the liability.

Rentals payable under operating leases, including any lease incentives received, are charged to profit or loss on a straight line basis over the term of the relevant lease except where another more systematic basis is more representative of the time pattern in which economic benefits from the leased asset are consumed.

Transactions in currencies other than pounds sterling are recorded at the rates of exchange prevailing at the dates of the transactions. At each reporting end date, monetary assets and liabilities that are denominated in foreign currencies are retranslated at the rates prevailing on the reporting end date. Gains and losses arising on translation in the period are included in profit or loss.

In the application of the group’s accounting policies, the directors are required to make judgements, estimates and assumptions about the carrying amount of assets and liabilities that are not readily apparent from other sources. The estimates and associated assumptions are based on historical experience and other factors that are considered to be relevant. Actual results may differ from these estimates.

The estimates and underlying assumptions are reviewed on an ongoing basis. Revisions to accounting estimates are recognised in the period in which the estimate is revised where the revision affects only that period, or in the period of the revision and future periods where the revision affects both current and future periods.

The estimates and assumptions which have a significant risk of causing a material adjustment to the carrying amount of assets and liabilities are as follows.

The key source of estimation uncertainty that has a significant effect on the amounts recognised in the financial statements is the calculation of amounts recoverable on contracts, which is defined in the turnover policy above.

At year end, the Group held goodwill of £1.1m (2023: £1.4m) and the company held investments of £6.5m (2023: 6.5m) in subsidiaries in respect of Thornton Tomasetti Warrington Limited and Thornton Tomasetti Romsey Limited. Impairment assessments on these balances requires the Board to make judgements about the future performance of group entities. The Board performs a formal assessment at each reporting date to determine if any impairment is required. That assessment applies judgements about the recoverable amounts, including in respect of the future growth of the business. The Board determined that no impairment of investment or goodwill was required based on forecasts. The company held investments in subsidiaries of £6.5m (2023: £6.5m) at the year end.

The Directors estimated that the useful life of goodwill to be 10 years and will be amortised on a straight-line method over this period. The Directors considered the useful life to be reasonable on the basis of the Group's fair review of the business and future developments.

The recoverability of intercompany debt remains a key area of judgement with the expectation being based on management's best estimate of recoverability.

The recoverability of debt remains a key area of judgement with the provision being based on management's best estimate of recoverability.

The average monthly number of persons (including directors) employed by the group and company during the year was:

Their aggregate remuneration comprised:

The directors received no remuneration from Thornton Tomasetti Holdings UK Limited.

The actual charge/(credit) for the year can be reconciled to the expected charge for the year based on the profit or loss and the standard rate of tax as follows:

Details of the company's subsidiaries at 31 December 2024 are as follows:

The following are the major deferred tax liabilities and assets recognised by the group and company, and movements thereon:

A defined contribution pension scheme is operated for all qualifying employees. The assets of the scheme are held separately from those of the group in an independently administered fund.

At the reporting end date the group had outstanding commitments for future minimum lease payments under non-cancellable operating leases, which fall due as follows:

The company is a wholly owned subsidiary of Thornton Thomasetti Inc, which is incorporated in the United States of America and has registered office of 51 Madison Avenue, New York, N.Y. 10010-1603, USA.