The provisions of subsection (3) below shall have effect in any case where, in relation to an asset to which this section applies, there falls to be determined by virtue of section 272(1) the price which the asset might reasonably be expected to fetch on a sale in the open market.

The assets to which this section applies are shares and securities which are not quoted on a recognised stock exchange at the time as at which their market value for the purposes of tax on chargeable gains falls to be determined.

For the purposes of a determination falling within subsection (1) above, it shall be assumed that, in the open market which is postulated for the purposes of that determination, there is available to any prospective purchaser of the asset in question all the information which a prudent prospective purchaser of the asset might reasonably require if he were proposing to purchase it from a willing vendor by private treaty and at arm’s length.