1N.I.Where a person defers his retirement from regular employment after attaining pensionable age, or has made an election by virtue of section 30(3) of the Act and has not revoked it, then for the purpose of calculating the graduated retirement benefit payable to him from the date of his retirement—
(a)there shall be added to the amount of the graduated contributions properly paid by him as an insured person one-half of the aggregate graduated retirement benefit which would have been payable to him for any period before 6th April 1979 (disregarding the effect of any order made under section 120 of the Act) if he had retired from regular employment on attaining pensionable age and had received that benefit for the whole of the period without any interruption or abatement:
Provided that, in computing the addition to be made in accordance with this paragraph in the case of a person who has made an election by virtue of section 30(3) of the Act (re-entry into regular employment) or the corresponding provisions of any earlier Act, no account shall be taken of any period between 6th April 1975 and 5th April 1979 (both dates inclusive) which falls between the date of that election and the date of his previous retirement; and
(b)the rate of his graduated retirement benefit shall be increased by an amount equal to the increments to which he is entitled under paragraph 3 below, but only if either—
(i)that amount is enough to increase the rate of the benefit by at least 1 per cent., or
(ii)he has attained pensionable age before 6th April 1979, and has either deferred his retirement before that date, or made an election by virtue of section 30(3) of the Act taking effect before that date or both.