Speaking to BBC News, Ms Welch said: "Boris Johnson said at the time of the last election that he would look at it with fresh eyes and new vigour and sort it out which is an acknowledgment of the injustice.

"That was reported in the press, it wasn't just anecdotal.

"Keir Starmer said that this is an injustice against 50s women and that he supported BackTo60.

"Also the House of Lords and House of Commons select committees have all said that 50s women are grotesquely disadvantaged."

READ MORE: State pension age: Backto60 vow to launch fresh appeal to Court

She added: It is 100 percent discrimination, there is no doubt about it and we are actively considering a (Supreme Court) appeal.

"We have submitted grave and systemic evidence to the CEDAW committee in Geneva and they're looking at making an inquiry into the way that they've treated 1950s women."

She added: "We've also got the people's tribunal which is going to be looking at discrimination against all women and girls.

"What we're going to do there is write up draft legislation to bring a women's bill of rights into domestic law. It's not over."

The women argued that raising their pension age unlawfully discriminated against them on the grounds of age and sex, and that they were not given adequate notice of the changes.

But in a judgment published on Tuesday, Master of the Rolls Sir Terence Etherton, Lord Justice Underhill and Lady Justice Rose unanimously dismissed the women's claim.

They found that introducing the same state pension age for men and women did not amount to unlawful discrimination under EU or human rights laws.

As part of their ruling, the senior justices said that "despite the sympathy that we, like the members of the Divisional Court (High Court), feel for the appellants and other women in their position, we are satisfied that this is not a case where the court can interfere with the decisions taken through the Parliamentary process".

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They said that "in the light of the extensive evidence" put forward by the Government, they agreed with the High Court's assessment that "it is impossible to say that the Government's decision to strike the balance where it did between the need to put state pension provision on a sustainable footing and the recognition of the hardship that could result for those affected by the changes was manifest without reasonable foundation (MWRF)".

A DWP spokesperson welcomed the ruling, saying: "Both the High Court and Court of Appeal have supported the actions of the DWP, under successive governments dating back to 1995, finding we acted entirely lawfully and did not discriminate on any grounds.

"The claimants argued that they were not given adequate notice of the changes to state pension age. We are pleased the court decided that due notice was given and the claimants' arguments must fail.

"The Government decided 25 years ago that it was going to make the state pension age the same for men and women as a long-overdue move towards gender equality.

"Raising state pension age in line with life expectancy changes has been the policy of successive administrations over many years."