(a) Where, in relation to an instrument to which this subsection applies -
(i) the instrument is one to which section 29 applies, that section shall apply to that instrument as if -
(I) the following subsection were substituted for subsection (2) of that section:
"(2) Notwithstanding section 43, where, in connection with, or as part of any arrangement involving, a sale of any land, a dwellinghouse or apartment has been built, or is in the course of being built, or is to be built, on that land, any instrument whereby such sale is effected shall be chargeable to stamp duty under the heading "CONVEYANCE or TRANSFER on sale of any property other than stocks or marketable securities or a policy of insurance or a policy of life insurance" in Schedule 1, as if the property concerned were residential property on an amount which is the greater of -
(a) any consideration paid in respect of the sale of that land, and
(b) 25 per cent of the aggregate of the consideration at paragraph (a) and t
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