Mr Portillo has now set the political world alight by admitting his homosexual past, as well as announcing yesterday that he will seek the Tory nomination.
Until recently, Mr Portillo had decided to seek a low- profile return to the Commons at the next general election rather than at a by-election at which he would attract massive media attention. There were other advantages, too. With William Hague still at base camp in the electoral mountain he has to climb, Mr Portillo knew his prospects of succeeding him as Tory leader would be enhanced if he were not associated with what many Tories regard as an inevitable general election defeat.
In the event, the safe seat of Kensington and Chelsea proved too tempting. Its Tory majority of 9,519 offered a good enough insurance policy against the "stop Portillo" vote that scuppered him in Enfield Southgate in the most shocking result of the 1997 election.
If running for the Tory nomination was a gamble, Mr Portillo has now decided to go for broke by confirming that he did have homosexual relationships while he was at Peterhouse, Cambridge. Tory officials believe he had intended for the bombshell to be dropped during next month's Tory conference in Blackpool.
Now Mr Portillo has unwittingly filled the news vacuum at the end of the political close season, and completely changed the nature of the Kensington and Chelsea contest.
Yesterday, Mr Portillo said: "I think if I had read this about someone else, my reaction would be `so what?' I hope that will be other people's reactions."
The reaction among senior Conservatives yesterday was not "so what?" but "why now?" Shadow cabinet members are bemused by Mr Portillo's timing. They do not believe admitting he had gay relationships 25 years ago will prevent him winning the Tory nomination, or the by-election itself. But even some traditional allies say the affair raises new questions about Mr Portillo's political judgement, which will continue to haunt him once the newspaper feeding frenzy over his private life has died down.
"The Tory party is much more tolerant than it was 10 years ago," said one senior frontbencher. "What people will remember is the way it emerged. The man has shown again that he is woefully lacking any judgement."
Even some fellow acolytes of Margaret Thatcher admit her protege is not good in a crisis. They are worried about previous gaffes - his ill-judged "who dares, wins" party conference speech when he was Defence Secretary, his botched leadership challenge to John Major in 1995; allies installed telephone lines in the house earmarked for his campaign headquarters but the challenge never came.
Despite Mr Hague's supportive words last night, close allies fear the Kensington and Chelsea by-election will now be dominated by the gay issue, much to the horror of local Tory activists.
Moreover, Mr Hague's carefully laid plans to unveil his key policies, due to start next week at a Shadow cabinet summit, will be overshadowed. So will the Blackpool conference, a vital showcase for Mr Hague. Mr Portillo's speech on the conference fringe is bound to steal much of the media spotlight.
One Tory frontbencher said Mr Portillo should have made his announcement about his sexuality two years ago, when he converted to "caring Conservatism" in a conference fringe speech, and called on the party to be more tolerant of minorities.
There is nervousness in Tory ranks about the possibility of further revelations about Mr Portillo's private life, however long ago the events took place. He may have been happily married for 17 years, but that will not stop the tabloids digging for dirt. Last night rumours were rife at Westminster of fresh allegations about his relationships.
According to some Tory MPs, the fear of such disclosures could harm Mr Portillo's prospects of winning a future party leadership race. The party is still haunted by the damaging spate of revelations about the private lives of ministers which turned John Major's "back to basics" initiative into a fiasco.
Some MPs are convinced that one reason Mr Portillo decided to set the record straight now was an attempt to prevent "dirty tricks" by potential rivals for the Tory crown.
He professes his loyalty to Mr Hague, who has said he would welcome his return to Westminster. But the two men have an uneasy relationship. Mr Hague's inner circle is convinced there is a cabal of "Portillistas" - and has removed some of them from positions of influence at Conservative Central Office.
Privately, the Hague camp would have preferred Mr Portillo to return at the general election. Although the Tories won the Euro elections in June, the grumbling about Mr Hague's performance has not died away.
At present, there is no alternative leader at Westminster. If Mr Portillo wins in Kensington and Chelsea, there would be. Even total loyalty would not stop the media speculating about a leadership challenge.
Tory aides argued yesterday that Mr Portillo's attempt to clear the air could boost Mr Hague's drive to portray a more modern image. So could a gay Tory leader broaden the party's appeal? Not necessarily, according to militant campaigners. Peter Tatchell, spokesman for Outrage!, said Mr Portillo would not be forgiven for his "hypocrisy" of rejecting gays in the armed forces and voting against lowering the age of homosexual consent to 16.
A Tory MP said: "We all suspected he had been gay and are quite tolerant of it. But the British public had no idea. I don't think they are ready for a high-profile gay Tory."Reuse content