He may not have been considered the most sexy candidate. But sex has certainly helped transform Iain Duncan Smith from relative unknown to probable front-runner in the Tory leadership race.

They were all "up for Portillo" again last Tuesday night. After his defeat at Enfield in 1997, the one-time darling of the Thatcherite right was shocked and humbled to find the national loathing of John Major's government so personally reflected in hostility to himself.

Shortly after five o'clock last Tuesday evening Mr Portillo learned that - his personal journey notwithstanding - such hostility continued unabated. Reliving that defining moment of New Labour's 1997 victory, Blair Babes squealed delightedly as the chairman of the 1922 Committee, Sir Michael Spicer, confirmed the Castilian's second - and, this time, seemingly final - fall.

Predictably, perhaps, they were well up for Portillo a second time around. Only this time - as he promptly confirmed his departure from front-line politics altogether - the former Tory golden boy knew "they" now included two-thirds of his own parliamentary colleagues.

Raw visceral dislike in the hours before the result of the third ballot was declared gave way to an arrogant swagger among sections of the Tory right, thrilled that the final choice for the Tory membership at large would be between the "true" Thatcherite Iain Duncan Smith and the famously Europhile Kenneth Clarke.

No matter Sir Nicholas Soames's warning that this titanic struggle might "make flesh" of the polarisation inside the Tory Party. No matter that the Eurosceptic Portillo's social tolerance might just have enabled the party to reconnect with the millions of conservative voters who have deserted it over two elections.

Better by far, reasoned right-wing commentators, a contest between two men prepared to connect with the issues of most concern to the members themselves. Better too, some argue, to leave the task of reconnection with the voters to a leader who has not grown disconnected from the party itself. For that, certainly, was among the deadly charges levelled against Portillo.

Iain Duncan Smith (47) is widely and routinely described as "a gent", an allround decent guy, heavily into "loyalty", not much inclined to dabble in the personal stuff. And he was generous in triumph, describing Mr Portillo as a good and decent man with a big future in politics still before him.

Some of his supporters, however, were far from hesitant about the personal stuff, and will be frankly content if Mr Portillo keeps to his word and "never again" sits on the Tory front bench. Lord Tebbit's boot was firmly directed at the Portillo groin, after all, when he famously described his successor as Chingford MP as "a remarkably normal family man".

By Monday night other Duncan Smith supporters had accurately called it: enough "confirmed wets" and devotees of the "big beast" concept to put Mr Clarke over the 56-vote threshold, with Portillo and their man battling to be standard-bearer of the centre-right.

And their quiet confidence was rooted in three messages apparently coming back from the constituencies. One, that popular hostility to the neo-Thatcherite Portillo had proved enduring. Two, that many were unimpressed with his reinvention as a "socially inclusive" Conservative and considered him "shifty". Three, that many grassroots members didn't care for "the Spaniard's" admission of a gay past.

It is difficult to weigh the competing factors which spelt the end of Mr Portillo's leadership dream. But it is clear that homophobic and, in some instances, racist instincts, were among them.

Portillistas were naturally disconsolate in defeat. "It's terrible," said one: "Simply terrible. Those bastards in the parliamentary party have learned absolutely nothing. All those people who think we are against them now have no reason to change their minds."

This, however, is hotly disputed by supporters of "IDS". The man himself certainly refutes suggestions he is the "no change" candidate. Significantly, in this context, it is noted that the former chairman Michael Ancram switched allegiance to Mr Duncan Smith in the belief that he would accommodate all shades of opinion within the Tory party.

Scots-born despite the cut-glass accent, Roman Catholic, son of a beautiful Cork ballet dancer who met his war-hero father in Naples, married to Betsy, daughter of Lord Cottesloe - Iain Duncan Smith once remarked of his mother's passion: "Ballet is about the feminine virtues. At the end of the day, the man supports the woman."

As leadership candidate, however, he has stressed the need to see more women in the Tory front line. He has also promised a rearguard action against the growing Liberal Democrat threat - which supporters take to presage much greater focus on local and community politics spoken increasingly with regional accents.

So a party led by him wouldn't be hirsute and homophobic, chauvinistic and authoritarian? "Absolutely not," insists one who knows him well: "Like most conservatives, he is traditional but tolerant at the same time."

There was a hint of that tolerance, perhaps, in a recent interview when the would-be leader was thrown when asked if he'd be delighted if his daughter became a lesbian. Recovering himself, the father of four replied with some tenderness: "Bringing up children is something you derive massive pleasure from. I hope my children will find similar happiness. You learn to love with open hands."

Iain Duncan Smith's ace-pilot father, "Smithy" - a man who despised politicians - was disappointed when his son left the army for business. He accepts that his sons, in turn, will at some point disappoint him.

Tory image-makers may have advised the former Guards officer to drop his habit of wearing a trilby and carrying an umbrella. But he is not apparently "the barking military man" when it comes to children. One female acquaintance, describing him as sensitive and gentle, says in fact "he understands what it feels like to be 12".

HE ALSO understands life on the dole, and the humiliation and terror inflicted by redundancy - ironically finding himself a victim of the Tory recession in the late 1980s. Supporters cheerfully observe he is unencumbered with ministerial responsibility for the failures of the last Tory government - he refused office to campaign against the Maastricht Treaty. They also say he has spent less time in parliament, and thus suggest he has greater recent understanding of normal life than any of the other four who originally entered the race to succeed Mr Hague.

Then Hague's social security spokesman, "IDS" left the politics of the Belfast Agreement to Andrew Mackay. Having served there in the early 1970s, he has no track record on Northern Ireland. That said, he was critical of the Blair government's failure to link prisoner releases to paramilitary decommissioning, and is "conventionally unionist-minded". Aides confirmed last night that Northern Ireland will be an early port of call as he takes his campaign to the Tory constituencies.

One constituency with no vote but eagerly cheering him on will be the conservative establishment in Washington. "IDS" scored a significant hit when the new US Secretary of Defence, Donald Rumsfeld, met him ahead of the British Defence Secretary, Jeff Hoon. And he appears to be having some success with the Bush administration in undermining Tony Blair's "Britain as bridge between Europe and America" stratagem.

Kenneth Clarke insists Europe should not be the defining issue in the leadership contest, and that the euro certainly will not be the issue on which the next general election turns. So far, however, the former chancellor appears to have talked of little else. And Mr Duncan Smith appears determined the issue must be settled.

If the preservation of British sovereignty remains the defining issue for the members, then Mr Duncan "Nation State" Smith will be their man.

And beyond that? Assuming he can prove that baldness is not an impediment to office, and that he isn't "William Hague's father", or Hague himself "without the jokes".

The modernising Portillistas will scoff. But one fan insists the "IDS" mission is, in the words of Lord Woolton in the late 1940s, "to make the party more like the Britain of today". His advantage over Portillo, he argues, is that "he will seek to change with the party rather than against it". And he promises to do so, not by converging on the already packed ground of New Labour's consensus, but by standing resolutely outside Mr Blair's famous "big tent".

If he is to have the chance to do so, however, Mr Duncan Smith - like Mr Clarke - must take care to ensure that the leadership battle leaves what remains of the Tory tent still standing.