A weakened Theresa May is facing mounting pressure to perform yet another U-turn over the campaign, supported by Tory and Democratic Unionist MPs, to give women born in the 1950s a “fairer” pensions deal.

The issue was raised during a passionate debate at Westminster, which heard from the SNP’s Mhairi Black about how she was told that a woman had killed herself after the General Election result had increased her worries over her future pension provision.

The campaign, Women Against State Pension Inequality[Waspi], wants the UK Government to compensate 3.5 million women caught up in the “unfair” accelerated policy to equalise the state pension age between men and women.

Changes to the pension age mean many women born in the 1950s will have to wait longer than expected to receive their state pensions. Some women claim they were not given enough notice to prepare for the changes while others say they were not notified at all.

For its part, the UK Government says it has already committed £1 billion to mitigate the impact of the changes, ensuring that no one would see their pension date move by more than 18 months.

However, following the General Election the political landscape has changed.

Alex Cunningham, the shadow pensions minister, highlighted how 37 Conservative MPs had previously supported the Waspi campaign, and how this number could “provide a majority” in the Commons to support its cause on any future vote.

Last month, a parliamentary motion on Waspi said Westminster had a “moral duty to ensure there is a fair transition for women born on or after 6 April 1951 regarding their pensions”. It was signed by five DUP MPs, including Sir Jeffrey Donaldson, the party’s chief whip.

During a packed Westminster Hall, Labour’s Grahame Morris, who led the debate, urged the Government to acknowledge its error and pay adequate compensation to the Waspi women.

He quoted from the DUP election manifesto, saying: “They would ‘support an end to the unfair treatment of women pensioners.’” He added: “Alongside those Conservative MPs who signed the Waspi pledge, we have the numbers to change this policy.”

Tory backbencher Tim Loughton, co-chairman of the all-party Waspi group, said Government policy was a “breach of trust” for millions of women, who had done the right thing by working and paying taxes. “This problem is not going to go away. I hope with a new minister and a new secretary of state, we recognise this injustice and do something at long last.”

Ms Black said she was "absolutely scunnered" about "banging on about the injustice" done to the Waspi women.

She told MPs: "I got an email today from a woman, a Waspi woman...and she was telling us that her friend committed suicide after the General Election result because she could not face what was going to happen to her.”

The MP for Paisley and Renfrewshire South noted how the Government had rightly dropped its manifesto plans on scrapping the pensions triple lock and means-testing winter fuel payments and urged it to “just drop one more plan”.

She added: "Realise this is cross-party, this is across different backgrounds, different areas, this is people's mothers, this is your aunties, this is your sisters and cousins. So please can we do the right thing, do the job of Government and fix the problem and start looking after your people."

Guy Opperman, the work and pensions minister, said the Government was willing to look into individual cases where women had difficulties because of state pension changes and do what it could to help.

With many MPs reacting with exasperation, he made clear it was “not the Government position that they are going to make further concessions” and stressed there was a “massive amount this Government has done on a progressive basis to get people back into employment or retraining in their pre-pension years”.

Afterwards, Jane Cowley, the Waspi campaign director, welcomed the Commons debate and said: “The campaign is gaining momentum and it is time the Government took us seriously. Today’s debate is just one example of how we will continue to fight this injustice.”