(1) Subject to this section, subsection (2) shall apply where -
(a) section 579B applies as regards the trustees of a settlement,
(b) after the relevant time (within the meaning of that section) a person disposes of an interest created by or arising under the settlement and the circumstances are such that subsection (4)(a) of section 613 does not apply by virtue of subsection (5)(a) of that section, and
(c) the interest was created for the benefit of the person making the disposal or that person otherwise acquired it, before the relevant time.
(2) For the purposes of calculating any chargeable gain accruing on the disposal of the interest, the person disposing of it shall be treated as having -
(a) disposed of it immediately before the relevant time, and
(b) immediately reacquired it,
at its market value at that time.
(3) Subsection (2) shall not apply if section 579E applied as regards the trustees in circumstances where the time concerned (within the meaning of that section) fell bef
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