Hundreds of thousands of mothers who gave up work to care for their children but missed out on pension credits because of poor record-keeping by the Government are in line for a windfall.

Files dating from the 1970s are to be reviewed to identify mothers who are owed a reported average of £3,000.

The Department for Work and Pensions and HM Revenue confirmed last night that they will carry out a search of national insurance records to find women who are over or approaching retirement age and are recorded as not being entitled to a full pension.

Mike O’Brien, the Pensions Minister, pledged that any losses of pension rights arising from miscalculations would be “remedied”.

Steve Webb, a Liberal Democrat MP who has campaigned on the issue, welcomed the development and said that the system had let women down.

The Times revealed in May that the shortfall could be up to £1 billion.

Usually, a person needs to work for 39 years to have sufficient national insurance contributions to qualify for a full state pension. But Home Responsibilities Protection, introduced in 1978, reduces the number of years women need to qualify. However no checks were made by the Child Benefit Office to verify national insurance numbers, which were administered by a different department, until 1994.

Many women were unaware that they qualified for protection and did not receive full pensions because the Government’s system failed automatically to adjust their qualifying years.

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