Intangible assets are stated at cost less accumulated amortisation and accumulated impairment losses. The assets are reviewed for impairment if the above factors indicate that the carrying amount may be impaired. Amortisation is included in 'administrative expenses' in the profit and loss account. Intangible assets are amortised over an effective life of 10 years.

Tangible fixed assets are measured at cost less accumulated depreciation and any accumulated impairment losses. Depreciation is provided at rates calculated to write off the cost of the fixed assets, less their estimated residual value, over their expected useful lives on the following bases:

Stocks and work in progress are valued at the lower of cost and net realisable value after making due allowance for obsolete and slow-moving stocks. Cost includes all direct costs and an appropriate proportion of fixed and variable overheads. Work-in-progress is reflected in the accounts on a contract by contract basis by recording turnover and related costs as contract activity progresses.