Ms Madden said: “The government has accepted that 1950s-born women are victims of maladministration, but it now says none of us suffered any injustice.”

With no compensation forthcoming she said: “The alternative is continued defence of the indefensible but this time in front of a judge.”

The Waspi group has also launched a crowd-funding campaign to try and cover an estimated £75,000 in legal fees.

If the women were to win their case its estimated it could cost the government as much as £10.5 billion.

With government finances already under strain because of weak economic growth and higher borrowing costs Sir Keir Starmer has said “the taxpayer simply can’t afford the burden” of compensation.

The changes were first decided in 1995 when the then Conservative government sought to equalise the age at which men and women received their state pensions, aiming that by 2020 everyone would have to wait until their 65th birthday.

However in the aftermath of the global financial crisis in 2010, the Conservative-Lib Dem coalition decided to speed up the changes, to reduce the overall cost of the state pension.

Other countries have made similar decisions in recent years however the UK government didn’t communicate its change quickly enough and the impact of that could now be examined in court.

A government spokesperson told the BBC on Sunday it accepted the ombudsman’s finding of maladministration and had apologised for the 28-month delay in writing to 1950s-born women.

“However, evidence showed only one in four people remember reading and receiving letters that they weren’t expecting and that by 2006, 90% of 1950s-born women knew that the State Pension age was changing.

“Earlier letters wouldn’t have affected this.”