To ask the Secretary of State for Work and Pensions if he will make an estimate of the cost of extending eligibility to buy back six additional years of national insurance contributions to (a) men and (b) women reaching state pension age in (i) 1978, (ii) 1988 and (iii) 1998; and if he will estimate the cost of such extension to all those reaching pension age within these time periods, regardless of qualifying years. (263150)