Harriet Harman has praised the “absolute heroism” of the Tory MPs who investigated Boris Johnson lies to parliament despite huge pressure from colleagues to quit.

The former deputy Labour leader, who chaired the Commons Privileges Committee, said she might not have withstood the pressure if the political tables had been turned.

In her first public comments on the process, she said: “Those four Conservative members of the committee did a heroic service on behalf of the House of Commons, because they were absolutely steadfast.”

Ms Harman, who entered the Commons in 1982 and is now its longest serving female MP, was speaking about her experience at the Edinburgh Fringe.

She told Iain Dale’s All Talk at the Pleasance EICC that she had not expected to chair the Commons committee, but agreed to step up after its usual chair, Chris Bryan, recused himself because he had previously criticised Mr Johnson.

The former Prime Minister quit as an MP after the committee found him guilty of serial contempts of parliament by lying about Covid rule-breaking in Downing Street.

The committee recommended that he should be suspended for 90 days to reflect the seriousness of his misconduct, which included contributing to a campaign of abuse and intimidation against the Committee while it was investigating him.

Four of the seven MPs on the committee were Conservatives - Andy Carter, Alberto Costa, Sir Bernard Jenkin and Sir Charles Walker.

The others were Ms Harman KC, the SNP’s Allan Dorans and Labour’s Yvonne Fovargue. 

Ms Harman said the Tory members had come under intense pressure to back away from the probe, including pressure from other Tories calling it a “kangaroo court” and biased.

She said the Committee had been scrupulous in following the evidence, and all its members appreciated the importance of the probe to the work of parliament as a whole.

She said: “It was very galling to see members of parliament say this is a kangaroo court. It wasn’t a kangaroo court, it was a committee of the House of Commons which they had asked to be set up, which they had set the terms of reference for, they’d agreed all the members of, and therefore… it was quite wrong for them to be criticising it.

“There was real pressure and real harassment of the Conservative members of the committee by Conservatives who support Boris Johnson and wanted to interfere in the decision that we might come to, and interfere with the process that we were undertaking.

“And really those four Conservative members of the committee did a heroic service on behalf of the House of Commons, because they were absolutely steadfast.

“They were getting rained down on by emails and people saying, You are a disgrace, get off the committee, you should not be doing this, this is a witch hunt’.

“And they were being so pressurised from their own side that they were like, This is the job that we’ve agreed to do, for the House of Commons, for our democracy, we are going look at the evidence without fear or favour and carry on doing it.

“I can honestly say that if I was one of them, and it was the other way round, it was a former Labour Prime Minister, I couldn’t necessarily say I would withstand all that pressure.

“When you can’t do the job you were elected to do because you've got all this pressure raining down on you, you’ve got to look at thousands of pages of documents, hundreds of photographs and not speak to anybody about it.

“I think that they did a really remarkable job for the House of Commons and for our democracy, and I was really in awe of them.

“I don’t think that was seen, but it was absolute heroism, I think. 

“It sounds a bit overstated, but when you’ve that much political pressure on you, to keep doing your job because you feel it’s your duty is remarkable.”

Mr Johnson quit as an MP after being shown the Committee’s draft report, triggering last month’s byelection in Uxbridge and South Ruislip, which the Tories narrowly held.

Ms Harman, 73, who is stepping down as the MP for Camberwell and Peckham at the general election, also revealed she regretted not insisting on being deputy Prime Minister to Gordon Brown when she won Labour’s deputy leadership contest in 2007.

She said she failed to appreciate the importance of a woman being deputy PM.

She also said she thought she would probably have won the Labour leadership after MNr Brown stood down in 2010, when she did not stand.