He quit as a minister immediately after the publication of a report in which he was sharply criticised by the Tory-dominated Standards and Privileges Committee which examined the allegation that he attempted to subvert a parliamentary inquiry into the Neil Hamilton "cash-for-questions" affair.
The speed with which Mr Willetts departed was intended to limit the damage to the Government, but did nothing to dispel the impression that this is an administration in its death throes.
His replacement was named last night as Michael Bates, the 35-year-old MP for Langbaurgh, who has been a government whip for more than two years.
Although the committee made no recommendation, Mr Willetts' resignation became inevitable because of the unequivocal, and strong, wording it employed and the use of the word "dissemble" in relation to his evidence.
The unanimous report said that its members "were very concerned that any member should dissemble in his account to the committee, and believe that this response by Mr Willetts has substantially aggravated the original offence".
Indeed, the MPs were more angered by Mr Willetts' performance when he appeared before the committee in October than the substance of the complaint, which was that in October 1994 he tried to influence the Hamilton inquiry. The feeling among the committee was that if Mr Willetts had said "sorry", he would have received a rap on the knuckles. But the fact that he gave such an unconvincing account made a strongly worded report, and therefore his fate, inevitable.
The Government immediately mounted a damage- limitation exercise, furiously attacking the committee for its findings and describing Mr Willetts as an honourable man.
"It is a grotesque and unfair judgement on a fine minister. He will be back. He is a man of honour and it was totally wrong," said one angry government whip.
Another whip said: "It is a travesty of justice. He was pursued by one man, Quentin Davies" - the Tory MP who gave Mr Willetts a relentless grilling when he appeared before the privileges committee.
Downing Street said the Prime Minister had not tried to persuade him to stay on. "Mr Willetts is an honourable man and he had said very firmly that he believed the only course for him was to resign."
The Tory MP David Martin, whose Portsmouth South constituency adjoins Mr Willetts' in Havant, blamed what he called the "boorish and bullying" behaviour of Quentin Davies for the strong language of the report.
The extent to which the MPs doubted the accuracy of Mr Willetts' evidence to them is shown by the fact that the committee has taken the unprecedented step of requiring future witnesses to give evidence to them on oath.
Mr Willetts' resignation letter said: "I am sorry my integrity has been called into question, especially as throughout the committee hearing I told the truth." However, he felt "the only honourable course is to resign".
The committee criticised Mr Willetts, then a junior government whip, for having discussed with Sir Geoffrey Johnson Smith, the chairman of the now-defunct members' interests committee, "a matter critical to the future deliberations of his committee" in October 1994.
Mr Willetts had discussed the Hamilton affair with Sir Geoffrey and then wrote a memo which implied that he had tried to ensure the committee either did not consider the Hamilton case, or undertook a quick inquiry that "exploited the good Tory majority".
However, the committee largely cleared him of the original allegation, saying there "was no clear evidence that Mr Willetts set out to influence Sir Geoffrey or that he succeeded in doing so."
Mr Davies's public grilling of Mr Willetts at the committee hearings six weeks ago was particularly damaging to the minister, and was singled out for criticism by Conservative colleagues. One said: "I would not like to be Quentin Davies tonight."
The committee, which took almost 20 hours of debate to reach its unanimous decision, was not split on party lines but a few of the Tories held out until yesterday against the strong wording of the report. The unanimity of the report, and its strong wording is a triumph for those MPs who have strongly resisted any outside involvement in the policing of their activities. By bringing all the members into line, it is a personal triumph for the chairman of the committee, Tony Newton.
The committee is now expected to consider the case of Andrew Mitchell, another former whip and now a minister, who is also the subject of allegations that he attempted to limit the inquiry into the Hamilton affair.
John Major told Mr Willetts last night that his resignation was "consistent with the dignified way that you have conducted yourself".
Ministers did not rule out the possibility that Mr Willetts could work for Central Office as political strategist in the election campaign, and predicted that he would back on the front bench after the election.