Iain Duncan Smith's clear victory begins a new phase in the life-and-death struggle of the Tory party to become electable again. What it does not yet mark is anything remotely like the kind of change Labour went through in the 1980s and 1990s.
The first, all-important caveat is that it is very dangerous to prejudge a party leader before he or she has had a chance to lead. There is no doubt that Mr Duncan Smith needed real steel to get this far.
In 1975, Margaret Thatcher was widely written off. History could not have more spectacularly mocked this judgement. It could just be that Mr Duncan Smith will turn out to be the second Neil Kinnock. The man who came to the party from the militant flank of Labour and a personal history of backbench rebellion to drag his party back to the centre where elections are won and lost.
It has to be said that this isn't how it looks at first glance. Instead, the Tory party appears to have performed the political equivalent of driving on ice: turn in the direction of the skid rather than try to fight it. Whether that works in politics, we will have to wait and see.
In this case, it appears very much as if the turn has been, in most respects, to the right. It's entirely true that Mr Duncan Smith proved to be, in the latter stages of his campaign, unexpectedly sensitive to the cause of social liberalism, for which some of his supporters denounced Michael Portillo in the parliamentary stages of this campaign. But this is not the only thing that distinguishes the right from the centre as well as from the centre-left.
Another is the role of the state, which the new leader has already indicated that he envisages as getting smaller, with greater reliance on private provision of health and education. That isn't what the country voted for by a large majority in 2001. The national mood could change, as it has in the past, if the Government is seen to be defeated in its struggle to modernise and improve the public services. But it is a gamble, as Mr Duncan Smith knows.
Another issue is Europe, which Mr Duncan Smith recently indicated he saw as the dominant one in British politics. It appears to have played a decisive part in his victory.
Indeed, the expectation by Clarke supporters of a division between activists who share the obsessive hostility of much of the parliamentary party towards the euro, and to some extent to the EU itself, and the silent majority of inactive party members, was disappointed.
A decade ago, the party would claim, whether credibly or not, something near a million members. As the total has fallen to its present level of less than 300,000, more of those remaining in membership turn out to have shared the activists' hostility to Mr Clarke's pro-European views.
Thus, the party has picked a candidate whose track record of Euroscepticism is, if anything, more entrenched than William Hague's. And when the British people have now twice voted for a broadly pro-European party not necessarily because they are pro-European but because many of them don't see it as the defining electoral issue.
Mr Duncan Smith has already shown that he has a number of assets, including a personable manner, a happy family and considerable self-confidence. He understands, perhaps better than his predecessor, Labour's ability to communicate its message. The party may, too, in the words of one of his supporters, have replaced a management consultant with an ex-Army officer who knows how to lead.
But he also faces real difficulties. One is what happens to broadly pro-European centrists in the party, starting with Mr Clarke himself. Both men were gracious about each other last night. But Mr Clarke was far from humiliated.
Will he simply withdraw from frontline politics? Will he in time become the effective leader of internal opposition to the new leader? Or will he something admittedly on the outside edge of present possibility consider forming his own, more centrist, grouping outside the official Tory party?
But Mr Duncan Smith's biggest problem, as the less popular man among the larger electorate, is to widen the narrow ideological base that chose him and opted against the wholesale changes that might have been expected after two crushing defeats. That process starts with the emergency debate which, in extraordinary, tragic circumstances, takes place in the Commons today.Reuse content