Where, on or after the commencing date, an eligible pensioner to whom pension is payable under section 52 of the Defence Forces Retirement Benefits Act 1948 is reclassified under section 53 of that Act, the rate at which pension is payable to him on and after the date from which the reclassification has effect shall be the rate at which pension would have been payable to him on the commencing date if he had been so reclassified with effect on and from the day immediately preceding the commencing date.