Alan Watkins: Mr Cameron has no choice. He will have to get his hands dirty like the rest of them

I doubt whether Her Majesty would simply send for Brown

Whether it was Mr Paxman or the Newsnight apparatchiks who made this decision, I do not know. Either way, it did not seem to me to be quite playing the game as far as Mr Cameron was concerned. If he had not been telling the whole truth, he should have been confronted during the interview rather than supplemented - or contradicted - after it had ended. In these circumstances, he might have been able to explain his votes against and his subsequent abstention. He was not given a fair or, indeed, any chance to do so.

Mr Paxman is a valuable part of our public life. There can be no question about that. But he is not a political specialist. To him, the minutiae of our own dear House of Commons are not a matter of great concern. And who shall blame him? He certainly does not spend part of his afternoons in the press gallery several times a week, as the late Sir Robin Day used to do. Instead he takes the world as his parish.

Actually I do not think even Sir Robin would have known about Mr Cameron's two negative amendment votes. Mr Paxman's solo intervention bears all the marks of the television researcher, of the bright girl or boy, recently down from the university, who has spent the last couple of weeks scrutinising Mr Cameron's division record. It may have been included in Mr Paxman's background material and he failed to mention it; or it may have been omitted altogether. Anyway, the mistaken decision was made to publish it after the interview was over. You cannot replay the game after the referee has blown the whistle.

Ill-natured persons (of whom I am not, I hope, one) might conclude that the episode provided yet another illustration of the BBC's tendency to favour the Government at the expense of the Opposition. Ministers tell whoppers all the time and go uncorrected by Mr Paxman or anyone else after the programme is over. For Mr Cameron, however, Mr Paxman's official statement is merely a beginning. Greater troubles lie in wait.

Leader of the Opposition is the worst job in politics. In recent times, I can think of only two who have done it successfully: Harold Wilson and Tony Blair. For Conservative leaders it is particularly thankless. Nor is this a recent phenomenon, dating only from 1997.

Until he won unexpectedly in 1970, Edward Heath spent his life surrounded by colleagues asking: Have we all made a terrible mistake? Margaret Thatcher seemed no match for James Callaghan, who specialised in patronising her: There, there, little lady, some of us have had experience of the problems of government. She was saved by Callaghan himself when he failed to go to the country in autumn 1978 and by what was then this great union movement of ours.

Like those previous leaders who went on to become Prime Minister, Mr Cameron has a full four- or maybe even five-year period of opposition in front of him, irrespective of whether it is Mr Blair or Mr Gordon Brown in Downing Street. There is not the slightest reason why the Government should fall, unless Mr Blair chooses to impale his colleagues on a measure (schools, hospitals, benefits: who can tell?) which he himself has chosen to turn into a vote of confidence.

In such an unlikely event, it does not seem to me that Mr Blair could choose to regard it as the loss of a vote of confidence in himself and expect the Queen to send for Mr Brown in his place. The Government would have to resign as a whole. Mr Blair could, of course, resign independently as Prime Minister irrespective of any vote of confidence, as Wilson did in 1976, and as he presumably still intends to do.

Here again I doubt whether Her Majesty would simply send for Mr Brown. Ever since 1963, when the Tories messily chose Lord Home, the Palace has embraced the formula "You choose, we appoint," as Sir Edward Ford, who was then the Queen's assistant private secretary, expressed it at the time. The Labour Party would have to go through its own formalities first, even if Mr Brown turned out to be the only candidate on offer.

There is a curious whiff of instability in the air. Mr Cameron will be expected to make things happen. If he is unable to bring the Government down - and only a few of the more hysterical Tories expect that - he is certainly expected to finish off Mr Blair in some way. The principal means of accomplishing this is through winning votes in the Commons or, at least, through forcing divisions in which the Opposition puts up a respectable showing.

But this is the very thing that the original Mr Cameron, at the beginning of his campaign, only a few weeks ago, said he did not want to do. The citizens, he said, were fed up with factitious conflict; with opposition for opposition's sake. He started off by welcoming Mr Blair's Education White Paper. Then he said it did not go far enough. Most recently, to Mr Paxman, he described it as "timid".

This may provide the pretext for voting against it when, in some form, it comes before the House. In all the excitements of the past few weeks, what most people seem to have forgotten is that rebellions against Mr Blair depend largely on divisions in the House. The defeat on 90-day detention could not have happened if the Conservatives had not taken up the final position which - reluctantly, doubtfully - they did. I am not saying that Mr Cameron, had he been in charge, would have supported the Government on this particular measure. But nevertheless his instincts are for conciliation.

Over ten years ago, on the death of John Smith, there was a curious movement to preserve what was called "The Spirit of John Smith". In fact he was a cheerfully sceptical - some would even say cynical - politician, with a prodigious appetite for large gin-and-tonics, of which he could shift four before dinner without difficulty. Quite why Smith was nominated as the secular saint of political sweetness and light remains a mystery. But the period lasted only a few days. Then it was back to the bad old ways. Mr Cameron may find that he is forced on to a similar path.