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:

All investment properties are carried at fair value determined annually and derived from the current market rents and investment property yields for comparable real estate, adjusted if necessary for any difference in the nature, location or condition of the specific asset. No depreciation is provided for. Changes in fair value are recognised in the income statement.

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.