The following provisions have effect for the purposes of this Part.
The following are treated as realised losses—
A "revaluation provision" means a provision in respect of a diminution in value of a fixed asset appearing on a revaluation of all the fixed assets of the company, or of all of its fixed assets other than goodwill.
For the purpose of subsections (2) and (3) any consideration by the directors of the value at a particular time of a fixed asset is treated as a revaluation provided—
Where—
an amount equal to the amount by which that sum exceeds the sum which would have been so written off or retained for the depreciation of that asset over that period, if that profit had not been made, is treated as a realised profit made over that period.