Brandon Lewis has said he is “confident” no pressure was put on Sue Gray to alter her report into partygate.
It comes after The Sunday Times reported details of an alleged Downing Street flat party were removed from the investigation into rule Covid breaking.
The paper reported Gray had pressure placed on her by senior members of Boris Johnson’s team to remove certain details and names.
In an interview on the BBC’s Sunday Morning programme, Lewis was asked to give a “cast-iron guarantee” Gray was put under “no pressure whatsoever”.
The Northern Ireland secretary said: “Not only am I confident of that, but I know Sue Gray well enough to know pressure on Sue Gray would not have an outcome.
“Sue Gray is not somebody who is pressured into doing things by anybody,” he said. “She has put out a report that she is happy with, that she is confident about.”
Lewis added he believed the senior civil servant, who on Wednesday delivered her 37-page report into events held in Downing Street and Whitehall during England’s lockdowns, had been given the “freedom and the space” she needed.
According to The Sunday Times, the so-called “Abba party” held in the prime minister’s flat on November 13 2020 was “tweaked” by Johnson’s chief-of-staff Steve Barclay on the eve of publication.
It is alleged an earlier draft of Gray’s report referred to music being played and stated at what time the gathering ended, but that the information was redacted.
Gray found that the prime minister – who is facing growing calls from Conservative MPs to resign over his handling of the so-called partygate affair – did attend the mid-lockdown gathering along with five special advisers, with “food and alcohol available”.
However, she halted her work having only collected “limited” information when the Metropolitan Police began their investigation.
There was no mention in her report of The Winner Takes It All and other Abba songs reportedly heard blaring from the Downing Street residence after the departure of Dominic Cummings, who was formerly the PM’s chief adviser, was announced amid a bitter power struggle.
Carrie Johnson was reportedly at the November event but was not named by Gray in relation to the flat gathering.
The official said she had not long been investigating the evening when Scotland Yard began its criminal investigation and, once the police work was complete, “concluded it was not appropriate or proportionate” to advance her own inquiries.
It was also reported that senior civil servants, including the head of the Civil Service Simon Case, No.10 permanent secretary Samantha Jones and Alex Chisholm, permanent secretary in the Cabinet Office, looked to lobby Gray to persuade her not to name individuals who attended the gatherings – events for which some government employees have subsequently been fined for attending.
It comes as the number of Tory MPs to have publicly declared they have submitted letters of no confidence in the prime minister continued to tick upwards.
Former health minister Steve Brine and Anne Marie Morris became the latest to announce they have called for a vote on the future of Mr Johnson’s premiership.
Sir Graham Brady, chairman of the 1922 Committee of backbench Tories, will be obliged to order a confidence vote if he receives 54 letters demanding one.