Alan Watkins: Mr Osborne is the fly in the ointment

The Conservative Party has history with Kenneth Clarke, but he's the warhorse who would clinch it for Mr Cameron

Political commentators abhor the assumption of inevitability. That is part of the job. Sometimes the inevitable does not happen. It did not happen with Harold Wilson in 1970, with Edward Heath in February 1974 and with Neil Kinnock in 1992.

In the last few weeks a consensus has been building up. It is to the effect that Mr David Cameron is not sure of winning the general election. The Tories are – to a certain extent, always have been – obsessed by John Major's victory on the soapbox. The worry is not that he won but that they might lose.

The worries have been multiplied in the last month. There have been a couple of unsure performances at Prime Minster's Questions. At all events, sapient observers pronounced immediately afterwards that the performances had been unsure. From my seat before the television set, I was less definite in my opinions. To me Gordon Brown was always the same boastful, charmless, bullying, even menacing self.

No doubt Mr Cameron made a mess of things over marriage and income tax. It is an intractable subject, as is all tax, not to mention marriage. Grey battalions of lawyer and accountants spend entire lives on both topics. The general impression that has been conveyed, however – not only about income tax but about public expenditure more generally – is that Mr Alistair Darling is being more detailed and open than Mr George Osborne.

This may be unfair. It may not have been Mr Osborne's fault, altogether. But he has about him a certain fly-by-night quality. The most reassuring change that Mr Cameron could make before the election would be to exchange Mr Osborne for Mr Kenneth Clarke. The City would be happier with Mr Clarke. The voters would be comfortable with him. Only the Conservative Party would be restive.

It is long history, that of the party and Mr Clarke: Mrs Thatcher and her fall in 1990, Europe, three unsuccessful contests for the leadership. In 2001 he was defeated overwhelmingly by Mr Iain Duncan Smith. They must have been mad. Quite clearly, from the voluntary exit of Michael Heseltine, Mr Clarke was the best man for the job. But the Tories would not have him.

Moreover, Mr Osborne is Mr Cameron's best friend, politically, in a manner of speaking. They have been on the long march through the institutions together. I refer to the institutions of the Conservative Party rather than to those of the Republic of China. The displacement of Mr Osborne would cause the most frightful upset, whether before or after the election. So Mr Cameron is – we are all – stuck with Mr Osborne as chancellor.

Even so, I cannot see how much difference it is going to make come polling day. The voters have made up their minds, and it is that they are not going to vote Labour. They may vote Tory, or Liberal Democrat or for one of the peripheral candidates, or for nobody at all: but they do not want Mr Brown to be in No 10 any longer. It is as simple as that. Or perhaps it is not so simple after all.

For surrounding the consensus which I outlined earlier – that Mr Cameron might not win outright – is a whole fog of wishful thoughts and untested assumptions. It has even been suggested that Mr Brown (or his Labour successor) could return as the head of a minority government. This would not necessarily mean that Labour would have to win the largest

number of seats, though short of a majority. The party, whether under Mr Brown or somebody else, could ally themselves with the Liberal Democrats to form some sort of government, to keep out the Conservatives.

This was what happened in 1924, when Labour took office while the Tories had more seats. What the former attorney general would call "the better view" is that, in modern conditions, the largest party would have to take office, irrespective of any arrangements with the smaller parties. It would still be possible for a Labour-Liberal Democrat administration to take power of a sort even though the Conservatives had more seats.

It just shows how desperate some Labour people are. The Liberal Democrats are perhaps more realistic. I never thought I would find myself writing the sentence that the Liberal Democrats were being more realistic. But it is clear to them and to Mr Nick Clegg that any chance of a profitable arrangement is now with the Conservatives.

Another sign of Labour desperation was over the debate on the alternative vote. The House agreed to a future vote – presumably to be incorporated in the election manifesto – on a referendum on AV. The legislation itself would have to come later. For myself, I hold a heretical opinion. I have a clear view of the alternative vote. I support it completely, in single-member constituencies.

Most people take one of two positions. One is that first-past-the-post is the foundation of life and liberty. The other position is that we should go over to some kind of proportional system. This last group is, however, prepared to accept the alternative vote as a "first step" towards full proportional representation. I prefer the alternative vote to PR.

The proposal – indeed, the establishment of the system – could have been introduced at any time, ready for the next election. All Mr Brown has done is try to buy support from the Liberal Democrats, as a generalised gesture of benevolence, and much good will that do him.

Both leaders are sucking up to their followers like mad over the question of MPs' expenses. I long ago stopped trying to make sense not only of the original rules – for that was difficult enough – but of the plethora of commissions, committees, inquiries and investigations. There are two people called Kennedy, persons of pomp and power, one named Sir Paul, the other Sir Ian; one a retired judge, the other someone of equal eminence in the field of medical ethics. So let that be a lesson to us all.

Three members of the House of Commons and one of the Lords are to be prosecuted. They are promising, or threatening, to plead the law of parliamentary privilege in their defence. The party leaders are united in wanting nothing to do with the defendants or with the political system which they are currently meant to be supervising.

The law of privilege is even more intractable than that of income tax, to which I referred earlier on. The freedom of speech in Westminster, which was originally framed to protect MPs against the Crown in 1689, has been interpreted to protect members from all kinds of ancillary activities.

In the 1990s, liberal opinion was united (myself excepted) in trying to prevent Mr Neil Hamilton from suing in the courts. The defence was based partly on parliamentary privilege. The law was modified slightly, through the intervention of a private member, and a complaisant Conservative government. The case came on, and Mr Hamilton duly lost.

The use of parliamentary privilege is subject to political fashion and the interests, as they see them, of political parties. Interests remain permanent for a long time, but fashion changes; just as the fashion is to depreciate Mr Cameron's chances of winning an outright majority.