This section applies where—
by virtue of section 127, on a reorganisation the original shares (taken as a single asset) and the new holding (taken as a single asset) fall to be treated as the same asset acquired as the original shares were acquired; and
on the reorganisation, a person gives or becomes liable to give any consideration for his new holding or any part of it.
Where this section applies, so much of the consideration referred to in subsection (1)(b) above as, on a disposal to which section 53 applies of the new holding, will, by virtue of section 128(1), be treated as having been given for the original shares, shall be treated for the purposes of section 54 as an item of relevant allowable expenditure incurred not at the time the original shares were acquired but at the time the person concerned gave or became liable to give the consideration (and, accordingly, section 54(4) shall not apply in relation to that item of expenditure).