Labour insiders fear Rachel Reeves’ tears during Prime Minister’s Questions “have made her unsackable”. The Chancellor cried in the Commons chamber on Wednesday as Prime Minister Sir Keir Starmer failed to back her remaining in position until the next general election.

The PM went on to back her unequivocally, saying later that day Ms Reeves would be Chancellor for a “very long time to come”. He also said it was “absolutely wrong” to suggest Ms Reeves’ visibly tearful appearance related to the welfare U-turn, which put an almost £5billion black hole in her plans.

Ms Reeves on Thursday declined to give a reason for her tears, telling broadcasters she was clearly upset, it was a personal issue and she would not give any details.

The value of the pound and long-term Government bonds slumped sharply after Sir Keir failed to immediately back the Chancellor. Gilts rallied and sterling steadied after the later reassurances from the Prime Minister.

A Government source has told the Telegraph Sir Keir appeared to tie himself to Ms Reeves after her tears. The source said they believed “she would go” at the start of Wednesday, then believed that was “confirmed” when they saw her crying at PMQs.

Another source told the same publication that images of the Chancellor in tears shown on television had “shored up her position”.

Speculation the tears came after an argument with Sir Keir or Deputy Prime Minister Angela Rayner have been denied. Ms Reeves rejected suggestions her tears were related to a conversation with Commons Speaker Sir Lindsay Hoyle just before PMQs.

Ms Reeves, speaking on Thursday, said: “People saw I was upset, but that was yesterday. today’s a new day and I’m just cracking on with the job.

“My job as Chancellor is to return the stability to the economy, bring investment into Britain, but most importantly to improve the lives of ordinary working people, which is why I’m so pleased that in this first year interest rates have come down four times, saving money for people with mortgages, I’ve been the Chancellor who’s increased the national living wage…so I’m proud of what we’ve done this last year.

“But is there more to do as a Government? Absolutely there is, and I’m going to get on with that job.”

This includes finding £5bn after the Government was forced to U-turn on its flagship welfare plans. She has promised to do so without raising VAT, National Insurance or Income Tax and by not breaking her fiscal rules.