March? I'll be at Twickenham on Saturday

Those lawyers who become Prime Minister show no greater disposition than the others to regard the law as an institution or abstraction deserving of any special respect: if anything, perhaps, the reverse. They tend to look on it as a convenient device, as do those paladins of finance, such as the late Tiny Rowland, who maintain whole rows of barristers to persecute their enemies and to justify whatever it is that they have already decided to do.

In this respect Mr Blair is no different from his predecessors, notably Lady Thatcher. Nor is he, in one sense, at odds with his party. Traditionally, Labour has viewed the law as a capitalist conspiracy designed to do down the workers: an attitude that has begun to change only in the last 20 years or so, when Tory ministers have found themselves criticised or even reversed by the judges virtually monthly under the novel doctrine of judicial review.

But in the People's Party there has always been an exception to this suspicion, which is international law as laid down by the United Nations. It is doubtful whether the party would have supported the Attlee government's military contribution to the Korean War unless action had not first been authorised by the Security Council. It would have been vetoed if the Russian delegate had not been away at the time.

Mr Blair is not an old party man. Quite the reverse: his stock-in-trade, till now highly popular with the consumers, is that he is nothing of the kind. But he knows the party (still, formally, the Labour Party) well enough to realise that his only hope of carrying it in an attack on Iraq lies in the support of the UN.

He did not put it in quite this way on Thursday evening when he was being questioned by Mr Jeremy Paxman, who was, I thought, even more effective than Sir Robin Day would have been as the representative of the viewers. What Mr Blair said was that effective action against Saddam Hussein required a coalition. In other words, there was safety in numbers, or the more the merrier. Despite my suspicion of every word Mr Blair utters, including "and", "the" and "but", I am prepared to accept that this is what he believes. But he believes it also because he knows his chances of survival as Prime Minister depend partly on a vote in the UN.

It is doubtful whether Mr George Bush understands this completely. His father did not understand it when Margaret Thatcher was deposed in 1990, just before the beginning of the Gulf War, which was quite different from the present conflict. That earlier war, by the way, provided the context of her words as she was leaving No 10: "I'm a very good back-seat driver." They were not used of Mr John Major – as, damagingly to him, they were assumed to have been – but, rather, of Mr Bush senior. His son almost certainly does not understand, has no conception of, the almost sacerdotal authority with which the UN has been invested by the Labour Party ever since its foundation.

Though on Thursday evening he looked a worried man, Mr Blair seems sure he will get his second resolution. This will presumably refrain from specifically authorising the use of force but instead restate that Iraq is in breach of its international obligations. As the boxing managers used to put it: "Our boy is quietly confident." One wonders rather whether he is not being over-confident, perhaps reasoning that the best way of making something happen is to claim that it is going to happen anyway.

Mr Blair has said that he will not accept an "unreasonable" veto from France, Russia or China, all permanent members of the Security Council. But they do not have to use the veto. They can simply abstain, as France, for one, shows every indication of doing. With 10 temporary members of the council, the total number required by the rules for such action as Mr Blair is contemplating is nine, or one more than would provide a simple majority. Accordingly, if three permanent members abstained, he and Mr Bush would need to secure the support of seven out of 10 temporary members.

In my experience, you can work out all the arithmetical possibilities in advance; draw sage deductions; arrive at apparently inevitable conclusions – and then something unexpected happens that no one could possibly have foreseen. So I will hazard only one prediction which may still be wrong: that in the Labour Party the question will turn on whether the UN has duly authorised what Mr Bush and Mr Blair have decided to do anyway.

The Stasi, or political police – who, for the moment, remain loyal to the leader – will say it has. They will be supported by Mr Iain Duncan Smith, inasmuch as he concerns himself with the UN, and by most but by no means all of the Tories. The Liberal Democrats may well be split. Mr Tam Dalyell, Mr George Galloway and many others will claim that of course the UN has not authorised the use of force. Or, if it has, it had no business to do anything of the kind. In any case, they may add, in a terminology that does not come naturally to them, such authorisation is a necessary but not a sufficient condition for military action.

How many of them will there be? The Stasi predict it will be 40 or, at the most, 50 malcontents – in a phrase which should be consigned to the cliche cupboard, "the usual suspects". But the group may well be larger. We shall know more clearly when the House debates the war, as Mr Blair promised on Thursday it would. One of the politicians commenting afterwards said this was not much use because by then the war would have started and no one would be able to do anything about it. This struck me as a somewhat churlish response: not only that, but unduly pessimistic as well.

For in a democracy, wars can always be stopped. Mr Tony Benn has instructed all opponents of the war in Iraq to turn out in Hyde Park on 15 February. For myself, I shall be watching England play France at Twickenham instead. Demonstrations rarely change things. All sorts of shady groups attach themselves to them. By contrast, special conferences often do alter the course of events. In 1969 a trade union conference at the Fairfields Hall, Croydon, rejected the Labour government's proposals in In Place of Strife; and they stayed rejected. The early 1970s saw two special conferences on Europe, one at the Sobell Centre, Islington, the other at the Central Hall, Westminster.

The National Executive Committee, poor reduced creature as it may now be, still retains the power to summon a special conference. This it should now do on the subject of Iraq. The conference might even consider the question of whether it wished Mr Blair to carry on.