19. The retirement compensation which may be paid to such a person as is mentioned in regulation 17 who has reached normal retiring age without previously having been in receipt of retirement compensation shall be the equivalent of the difference between the pension and the lump sum or either of them paid to him under the relevant pension scheme and the pension and the lump sum or either of them to which he would have been entitled under that scheme if,—
(a)where retirement compensation is payable by reason of loss of employment, there had been made, in addition to the actual contributions made, the further contributions which, by virtue of regulation 18, are deemed to have been made,
(b)where retirement compensation is payable by reason of diminution in emoluments, there had been made the increased contributions which, by virtue of that regulation, are deemed to have been made,
subject to any deduction for a redundancy payment effected in accordance with regulation 27.