3U.K.Section 273 shall apply for the purposes of determining the market value of any asset at any time before 6th July 1973 [1973 c. 51.] (the date when the provisions of section 51(1) to (3) of the Finance Act 1973, which are now contained in section 273, came into force) notwithstanding that the asset was acquired before that date or that the market value of the asset may have been fixed for the purposes of a contemporaneous disposal, and in paragraphs 4 and 5 below a “section 273 asset” is an asset to which section 273 applies.