THERESA May has refused to guarantee that the “triple lock” on pensions will continue after being pressed on the matter by Angus Robertson in the final session of Prime Minister’s Questions before the snap General Election.

The SNP’s Westminster leader yesterday put May on the spot as the two leaders clashed in the Commons before they take to the campaign trail ahead of the June 8 ballot.

She and other senior ministers have repeatedly failed to guarantee the future of the triple lock, which ensures pensions increase in line with wages, inflation or by 2.5 per cent – whichever is highest.

The Prime Minister did say that pensioner incomes would continue to rise under a Conservative government, but her failure to guarantee the triple lock prompted Robertson to respond that the Tories could not be trusted on pensions.

May said:”I’ve been very clear that under this Conservative government, we have seen pensioners benefit as a result of what we’ve done to the basic state pension to the tune of £1250 a year. I am clear that under a Conservative government, pensioner incomes would continue to increase.”

Robertson responded: “I asked the Prime Minister a pretty simple question, it was a yes or a no, and the Prime Minister failed to answer.

“So pensioners right across this land are right to conclude that this Tory Prime Minister plans to ditch the triple lock on the state pension.

“Too many women already face pensions inequality, and the Tories now won’t even guarantee the pensions triple lock, and the only reason that they will not guarantee it is because they want to cut pensions.

“Is not the message to pensioners you cannot trust this Prime Minister, you cannot trust the Tories on your pension.”

With just 53 days to go before the poll, the record 58-minute-long session of PMQs was frequently rowdy as May faced questioned from the opposition parties.

A Labour MP accused her of being afraid to defend the record of seven years of the Conservatives in power at Westminster by refusing to take part in a TV debate. And after MPs left the chamber the issue surfaced again when a Labour spokesman confirmed Jeremy Corbyn would not take part in a televised debate unless May did so.

A Corbyn spokesman: “Jeremy will not take part in an opposition leaders debate. The British people have the right see a head-to-head debate between the only two people who could form the next government – and the Prime Minister’s refusal is a sign of weakness, not of strength.”

As the revelation first surfaced Nicola Sturgeon tweeted: “Faced with an open goal, Corbyn decides against even attempting to score.

Unbelievable, if true.”

During PMQs Corbyn faced accusations from May that his allies believe he is “not fit to run this country”.

The Prime Minister held up a piece of paper highlighting the website I Like Corbyn, But... , which she told MPs had been shared on Twitter by shadow home secretary Diane Abbott. Corbyn asked May a series of questions from members of the public about the NHS, education, pensions and wages, noting this was different to “hand-picked audiences who can’t ask questions” the PM is used to dealing with.

The Labour leader also accused May and the Conservatives of being “strong against the weak and weak against the strong”.

Speaking during Prime Minister’s Questions, May said: “I did note this week the shadow home secretary has been campaigning in her own personal way. She has directed her supporters, her followers to a website I Like Corbyn, But... .

“It says ‘How will he pay for all this?’, ‘But, I’ve heard he wants to increase taxes’, ‘But, I’ve heard he’s a terrorist sympathiser’, ‘But, his attitudes about defence worry me’.

“They are right to be worried. Unable to defend our country, determined to raise tax on ordinary workers, no plan to manage our economy.

“Even his own supporters know he’s not fit to run this country.”

Corbyn replied that his question was about the NHS and the concerns of a member of the public.

At this point, a Tory MPs started shouting “But”, with Corbyn adding: “The NHS has not got the money it needs, the Prime Minister knows that. She knows waiting times and waiting lists are up, she knows there’s a crisis in almost every A&E department. Maybe she could go to a hospital and allow the staff to ask her a few questions.

“Strong leadership is about standing up for the many, not the few. But when it comes to the Prime Minister and the Conservatives, they only look after the richest, not the rest. They are strong against the weak and weak against the strong.”

After PMQs, a Conservative spokesman said: “The Prime Minister was very clear that in the future pension incomes will increase.”

Andrew Gwynne MP, Labour’s national election chair, said: “Theresa May talked about the triple lock like it’s a thing of the past and, under the Conservatives, it risks being consigned to history.

“We will protect the incomes of 12 million pensioners across the UK by legislating to keep the triple lock.”