Under section 59 of the Social Security Pensions Act 1975 (c.60) the Treasury have to provide by Order for the increase in the rates of public service pensions. The Pensions (Increase) Act 1971 (c.56) defines certain terms and sets out when a pension “begins” (the day after the last day of service in respect of which the pension is payable) and how the increase applies to lump sums.