Question to the HM Treasury:

To ask Mr Chancellor of the Exchequer, what estimate he has made of the cost to the public purse of raising the basic state pension by (a) 10, (b) 15 and (c) 20 per cent.

Forecasts of expenditure on the basic State Pension are published at:

https://www.gov.uk/government/statistics/benefit-expenditure-and-caseload-tables-2014

In 2015/16 this is forecast to be approximately £68.45 billion in cash terms.

This can be used as the basis for calculating simple percentage increases.