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:

Investment property relates to fair value at the date of the revaluation less any subsequent accumulated impairment losses. Revaluations are undertaken with sufficient regularity to ensue the carrying amount does not differ materially from that which would be determined using fair value at the balance sheet date. No depreciation is provided for.