Turnover comprises the invoice value of goods and services supplied by the company, exclusive of trade discounts and value added tax.

Income in relation to consultancy and security checks is recognised when the work is carried out. Income in relation to testing contracts is received in advance of the service being provided, and consequently is apportioned equally to the profit and loss account over the contract period, with revenue related to services being provided in a subsequent accounting period being recognised as deferred income.

Current tax represents the amount expected to be paid or recovered in respect of taxable profits for the financial year and is calculated using the tax rates and laws that have been enacted or substantially enacted at the Balance Sheet date.

Deferred tax is recognised in respect of all timing differences that have originated but not reversed at the balance sheet date where transactions or events have occurred at that date that will result in an obligation to pay more tax in the future, or a right to pay less tax in the future. Timing differences are temporary differences between the company's taxable profits and its results as stated in the financial statements.

Deferred tax is measured on an undiscounted basis at the tax rates that are anticipated to apply in the periods in which the timing differences are expected to reverse, based on tax rates and laws that have been enacted or substantively enacted by the Balance Sheet date.