Bye. Bye. Put the phone down. No, you put the phone down."

By the time he actually gets into the car to be driven down Downing Street for the last time, we will all have forgotten why he is going.

Much of the explanation for Thatcher's blub on her exit must have been simple shock at the speed of her dispatch . . . not that there was ever much danger, for a man of Blair's self-control, of his repeating that part of the performance.

But the other reason why the air is not thick with cries of betrayal is that Blair never created a personal following in the Labour Party or the press on the Thatcherite scale.

That Blair has been betrayed, however, should not be in doubt. He is too clever to admit it, of course, because that would be to expose the weakness of his position. But he has been in a perilously weak position ever since half his backbench MPs voted against him on the Iraq war.

That is the real story behind his promise in September 2004 not to fight a fourth election: it was not a mistake, it was a tactic of self-preservation. And it is why he will tender his resignation from the office of prime minister on 27 June this year rather than at the end of next year, which would have given him a longer stretch at the top than Thatcher herself.

He was right to say, as he did in his resignation statement in his constituency of Sedgefield on Thursday, that 10 years of him was "long enough" for the British people. But only because his party had so lost the will to live, let alone to defend vigorously the achievements of one of the finest governments in modern British history.

They will be sorry when he's gone. They will be particularly sorry when they realise how casually disdainful they had become about one of the most successful and long-lasting leftwing governments in the developed world. It may not be left-wing enough for them, but that is sort of the point, isn't it? If it had been, it wouldn't have lasted.

The rest of Britain will be sorry, too. Well, all right, not sorry exactly. The average British voter is an unsentimental animal, and can "move on" from an ex-prime minister quite as callously as Blair was able to move on from sacking his ministers, as Alastair Campbell once revealed. But the moment those that have been built up and torn down are out of the door, much of the bitterness directed at them is drained and rehabilitation quickly becomes possible.

And the remembered-Blair will immediately become a template against which both Gordon Brown and David Cameron will be measured.

Measured and found wanting. In both cases.

It will be a while before we see a politician in Britain with the sheer bravura cheek of Blair, for example.

The chutzpah of someone who can apologise on behalf of his party for its folly in getting rid of him, as he did when he was forced to put a 12-month limit on his time in office by the coup of last September. "The first thing I'd like to do is to apologise actually, on behalf of the Labour Party for the last week, which, with everything that's been going on back here and in the world, has not been our finest hour, to be frank."

Well, someone had to do it, and sometimes if you want a job done properly, you've got to do it yourself.

But the Labour Party ought to apologise for forcing out a global statesman of such stature, a national leader of such articulacy and a social reformer of such energy. It ought to apologise for conniving in a media culture that has, on the basis of opposition to the invasion of Iraq, become nearly nihilistic about the possibilities of politics.

The problem for the Labour Party is that this media culture is not evenhanded. It does not treat government and opposition the same. Brown has to fight the tide of anti-government opprobrium that has already largely shifted from Blair to him, while Cameron is being given an easy ride.

Now is hardly the time for Labour to bring on the Second XI. Not that Brown is anything like as flawed as his detractors claim. As we saw last week, he is a better, more relaxed and witty speaker than the caricature painted by his enemies. He will make a good prime minister of Britain, albeit not as good as Blair. He would make a better prime minister, I think, than Cameron, who falls short . . . to use the vogue phrase of last week . . .

of the Blair standard in different ways. Brown is Blair Heavy; but Cameron is Blair Lite.

Brown made a good speech at his leadership launch on Friday. It certainly exceeded the low expectations that had been set for it by much of the press. It was encouraging that he promised to press on with the "important structural changes" in schools, in partnership with "teachers, parents, pupils and business", the fourth being the most significant.

"That sounds like Blair plus, " said one Blairite minister to me with detectable relief.