What explains Blair's curious reluctance to take public charge of this global disaster?

The PM who barely said a word in the first week of the disaster simply isn't the same Blair of even a few years ago

There is a mystery surrounding Tony Blair's discreet return to London from holiday yesterday and it is why he has so singularly failed to rise to the occasion of the tsunami tragedy. It is not a question of whether he should have remained on holiday or not. You can argue it both ways: that the country needed a voice for their concerns or that it doesn't make much practical difference whether he was here or there. Nor is it simply a matter of public expectation. After Iraq, there are an awful lot of voters who have had quite enough of Mr Blair's brand of caring concern without wishing more of it on this occasion.

The oddity is simply that the Prime Minister, who barely said a word during week after the disaster and only gave one rather abstract television interview, isn't the Tony Blair of five or even a couple of years ago. The parallel is not so much with the death of Diana as with 11 September. Then Mr Blair caught exactly the mood of grief and of resolution in his first reaction at the TUC conference, in his speech to the Labour conference and in his visit to the US. It was President Bush, slow to react and uncertain in his response who seemed the lesser politician.

Now it is the other way round. After an initial silence, it has been Mr Bush who has taken to the cameras and put his mark on America's response and Mr Blair who seems reluctant still either to comprehend the magnitude of the disaster or to try and ride the wave of compassion that has followed. Here is Bill Clinton's greatest pupil in the politics of tone. How can he have missed out on such a moment?

All sorts of reasons have been put forward for the change. The simplest is the human one. After seven years in power, under unrelenting pressure, politicians do genuinely need time off with their family. Mr Blair is not a man who shows the kind of agonising self-doubt that have crippled predecessors such as Anthony Eden and Jim Callaghan. If anything he seems entirely comfortable with power and its exercise. But the strain on close relations can be huge. The need to devote more time to your family is not just an empty phrase for departing ministers.

Yet those who seek power must be prepared to sacrifice for it - a point which ministers seem reluctant to grasp. Quite aside from the personal, there is something different about the Prime Minister today from the Tony Blair of yesterday. It's partly the attrition in his private office. Robin Butler, former head of the civil service, was last month bemoaning the decline in cabinet government in favour of a presidential style of centralised decision making - a complaint voiced widely in private by senior civil servants. But the interesting thing is not the sense of control by Number 10, strong though that was in the early years, but the extent to which it has been contracting in on itself of late.

The Prime Minister has lost most of his early companions in the inner sanctum, to be replaced by much more conventional types, and he himself has seemed less confident in his decisions. I don't think that he would have been so backward in coming forward had Alastair Campbell still been there. Nor do I think he would seem so divorced from the action had it not been for Iraq.

The effect of that fateful decision to go along with the invasion has changed all for the Prime Minister, not least his own sense of the public mood. To this day he seems to find it hard not so much to acknowledge as to understand why so many continue to be quite so angry about it. "Why can't people," he is wont to complain, "learn to accept my sincerity in going to war just as I accept their good faith in opposing it."

That argument will probably never be settled. But its effect has been to undermine the Prime Minister's confidence in his own touch. Like an actor, a politician needs the sense of connection with his audience to keep going, which is why so many retreat to their core supporters when the going gets rough. But Mr Blair has no natural constituency to fall back on and the lack of it shows in the curious loss of electricity in his public performances ever since Dr Kelly's death rudely interrupted his triumphal visit to Washington and China in 2003.

The war - and Mr Blair's own natural way of doing things- also helps to explain the recent pattern of his behaviour in which the Prime Minister absorbs flack for a time, makes a sudden move to regain the initiative and then lapses back, as if surprised and confused by the consequences of his action. He did it with his u-turn over holding a referendum on the European Constitution, with the promise of a Middle East peace conference in London and the appointment of Alan Milburn to oversee the election campaign. In each case the move has been swift and surprising but has had no follow-up, as if the decision alone was sufficient.

The same may well prove true of the tsunami: at first nothing, then the announcement of some great initiative to do with rebuilding or whatever, and then nothing much again. For the first week the Foreign Office refused to give the numbers of British missing, for fear of embarrassing the Prime Minister, but then decided to give a figure just as he returned. Next step no doubt is a memorial service in somewhere grand before the subject slips away again.

Does it matter that much? Not in conventional political terms. The opposition, although edging into the subject in the last couple of days, have kept clear of direct criticism of Mr Blair's refusal to cut short his holiday. President Bush recovered his reputation in the US after 11 September over time and presumably Mr Blair can in this case. He will make much of long-term reconstruction as a means of masking short term tardiness. But in terms of the public's view of him, he has missed a moment and that does matter.

Jack Straw, the Foreign Secretary, has made much of the point that Mr Blair's early return would have made no difference to the actual decisions made. But the public have a right to a voice from the top when they feel as concerned as they are over this disaster. And you have only to look at Winston Churchill's record to see that prodding, pushing and irritation from the top can make a difference. Would it really have taken a full week for the first RAF plane to arrive in the Indian Ocean if there had been an urgent voice from above?

In a deeper sense, too, this has been an important moment in the public polity of the country. Just as with Iraq, a huge swath of the public, both here and abroad (and it has been a global outpouring of compassion), have moved out of the parameters of party debate to express what they want from the world of tomorrow - which is real co-operation and real action to reduce the gap between the worlds and reduce their tensions.

Mr Blair had planned to meet these aspirations by making a series of set-piece moves on Middle East peace, African debt and climate change. But this is dead-ball play. What the public wanted this time round was a captain who'd go for the ball as it was played. Mr Blair let it pass. Is it possible the real reason is that he's losing his appetite for the game?

a.hamilton@independent.co.uk