At last the Blairs have learnt that you can't fool all of the people all of the time

The Prime Minister has built his entire political career on foolery, yet that essential art may now be deserting him

It is all very odd and it is still not over. The Cherie Blair imbroglio will have lasting consequences, in that it will sabotage her husband's attempts to refute Abraham Lincoln on fooling the people. Yet the oddest aspect of the whole affair is the way in which the principals have seemed determined to act out of character and to deny the claims of common sense.

Readers will be astonished to learn that I am not part of Mrs Blair's circle. But I had thought that there were some clues to her personality. As she is a serious lawyer, a devout Catholic, and a socialist, she would surely shun both dubious commercial associates and new-age surrogate religions, while regarding life-style gurus as a frivolous indulgence for overpaid yuppies. Evidently not.

In one respect she did run true to form. She has inherited her father's thespian talents. Tuesday's performance was impressive, with the pauses and the trembling lips coming bang on cue. It takes a good actor to rehearse spontaneity.

Not that there was anything spontaneous about her text. There, she was helped by Peter Mandelson, Charlie Falconer, Alastair Campbell and his partner Fiona Millar – who is Mrs Blair's press officer, working for a boss who tries to keep clear of the press, and paid for by the taxpayer. This drafting team ensured that the language harmonised with the desired emotional impact; never "my husband", always "Tony".

The Blairites are convinced that they can never go wrong by appealing to the British public's mawkishness and sentimentality. The aim was to present Mrs Blair as a put-upon mum who might make mistakes but was just trying to help the kids, and to accuse anyone who persisted in doubting her of hate crimes against all mothers and all children.

This might have worked, but only if the first night had been the sole performance. For that to happen, everything that could possibly come out had to be brought out and acknowledged. If anyone should have understood this, it ought to have been Peter Mandelson, who had to resign because clumsy delays in releasing information about his – trivial – role in the Hinduja degringolade gave the appearance of duplicity. He would surely have reminded Cherie that in politics, a cover-up can often be worse than the crime. Yet she continued, as she has throughout, to economise with the truth to the point of prevarication.

It is hard to resist the suspicion that there is a reason for this, and that further embarrassments are on the way. Who conceals when there is nothing to conceal? This is the obvious explanation for Number 10's conduct over the past few days. The Downing Street machine has never given the impression of believing that the whole matter had been put to bed on Tuesday evening. On the contrary: its behaviour is best described as frantic. Moreover, we still need to know how the tape of Peter Foster's conversations reached The Sun.

Foster may be a trifling creature, but he has unwittingly illuminated a great issue, in that he may well induce us to revise our opinions on transportation. The Ashes season has led many to believe that humanitarians were right, and that it was a tragic error. Then along comes Foster, who deserves nothing less than Botany Bay. In his prime he was, apparently, an accomplished con man who could have sold the Mayor of Paris the Eiffel Tower. These days only a fool would believe his unsupported testimony. But will it be unsupported?

Yesterday's papers were full of photographs of the Blairs in lovey-dovey mode. There were even suggestions that Tony would be spending more time with Cherie (Gordon Brown would have read that with interest). More cynicism, more mawkishness – more anxiety as to what the next set of headlines will reveal. In little more than a week, the purchase of flats in Bristol via a crooked intermediary has moved from peccadillo to panic.

Even when that subsides, the damage will remain. Mr Blair's moral authority has been compromised, just when he needs it most, and this will affect a number of public policy questions.

The Government is planning to raise more money from university students and/or their parents. If universities are to be properly financed, there is an overwhelming practical need for such a measure, and there is also a strong moral case. Because of Cherie, that case will be harder to meet. If the outcome is paying more money, there can be a lot of consumer resistance to the logic of moral argument, and many sorely pressed parents will now feel further emboldened. "It's all right for those Blairs: they can spend half a million quid on student flats and she has £50,000 a year to blow on taking showers with other women. They don't understand how real people live."

Up to now, the Blairs have managed to seem simultaneously a glamorous couple and an ordinary family. The glamour is now tainted: the ordinariness exposed as bogus. As a result, it will be harder for the Government to reform university finances.

It will also be harder for Britain to contribute to the war against Saddam. In Washington last week, I found the Bush administration remarkably well informed about the divisions in the Parliamentary Labour Party. (The political reporting from the US embassy in London is clearly excellent, possibly because of an outstanding second in command, Glyn Davies; there is no abler diplomat in the American foreign service). I was told that one reason why the President feels such affection and respect for Tony Blair is his awareness that only a minority of Labour MPs support the PM's line on Iraq. Old Labour dissidents will not be discouraged by the behaviour of New Labour's first family. Mr Blair will continue to support Mr Bush, but will pay a higher price for doing so. His family's recent troubles have also made a euro referendum less likely.

It is not only Labour MPs who are increasingly aware of sleaze, and increasingly disillusioned. If Mr Blair were to go on television now and try to bat away another problem as he did the Ecclestone affair by asserting that everyone knew him to be a pretty regular sort of guy, the derision would re-echo from one end of the kingdom to the other.

Apropos of kingdoms, during the Blairs' visit to Balmoral in the autumn of 2001, another guest asked Tony why he was so concerned about fox hunting. "I wish the whole thing would just go away," replied the PM. From across the table, there came a taut, angry hiss from his wife. "Tony, you promised." Those who are determined to resist a ban on hunting will not be deterred by the fact that someone who feels it necessary to employ a life-style consultant is trying to destroy their way of life.

Lincoln said that it was impossible to fool all of the people all of the time. Tony Blair begged to differ, and spent several years trying to prove that great president wrong. But the whirligig of time brings its revenges. Tony Blair has built his entire political career on foolery, yet that essential art may now be deserting him. If so, we are in for an interesting new year.