Suspicion was cast over Conservative MPs and a stream of damaging headlines were printed in the four days between claims that a member of the party viewed pornography in the Commons and Neil Parish’s resignation on Saturday.

The senior backbencher’s initial silence, followed by his insistence that he would stay in the job after he was named on Friday, have all helped prolong the torrid affair for the Tories.

Criticism has also been aired at the Tory whips for taking days to suspend him in the run-up to next week’s local elections.

It was at a meeting of female members of the Conservative 2022 group in Westminster on Tuesday night when the allegation first emerged. Two women said they had witnessed a male colleague watching pornography. One, a minister, said she had also seen him viewing adult material in a committee meeting.

Reporters learned of the allegations the following morning, but not the name of the culprit, with the Conservatives keeping that quiet.

Tory chief whip Chris Heaton-Harris responded by calling the behaviour “wholly unacceptable” and launching an investigation.

After demands for firmer and faster action, he called for the case to be referred to Parliament’s Independent Complaints and Grievance Scheme (ICGS).

The watchdog that investigates allegations of harassment and sexual misconduct went on to open an investigation after a referral from at least one of the witnesses.

Women in parliament came forward to decry the “shameful” culture at the heart of British democracy and international trade secretary Anne-Marie Trevelyan described once being “pinned up against a wall” by a former MP.

The prime minister, Boris Johnson, said the porn-watching was “clearly totally unacceptable” but urged people to await the ICGS investigation.

On Friday, the Telegraph approached the Conservatives saying it was preparing to reveal that it was Parish at the centre of the allegations.

Heaton-Harris released a statement saying he was suspending the Tory whip from the 65-year-old MP for Tiverton and Honiton.

Journalists tracked Parish down to his Somerset farmhouse, where his wife learned of the news from a reporter and both faced uncomfortable questions. Sue Parish said “it was all very embarrassing” as she defended her husband: “He’s quite a normal guy, really. He’s a lovely person. It’s just so stupid.”

Asked if he had opened something in error in the Commons, the MP said: “I did, but let the inquiry look at that.”

But on Saturday the pressure intensified. A Conservative source told the PA news agency it was likely that Parish would now be resigning within hours, with a second local source suggesting allies in Westminster were urging him to quit. Party sources said that pressure was not coming from Tory HQ.

His resignation will trigger a byelection in the Devonshire constituency that is historically safe for the Tories. The Liberal Democrats will relish the chance to snatch it though.

Parish will continue to face an investigation by the ICGS and questions as to why he did not save the Tories’ blushes in the run-up to Thursday’s local elections by resigning days earlier.