I USUALLY JUDGE the movement of opinion polls by the zones in which the various parties are placed, not by movements of single points, which can be almost random or depend on minor differences of methodology.

For 13 years before David Cameron’s election as leader, the Conservatives were usually stuck in the zone from 30 to 34; at the last general election, they won 32.3 per cent of the United Kingdom vote. Since Mr Cameron became leader, most polls have shown the Conservatives in the zone from 35 to 39 per cent. A BPIX poll in The Mail on Sunday now puts the Conservatives on 37 per cent, Labour on 36 and the Liberal Democrats on 17.

At a general election that would not give the Conservatives an overall majority. It represents a 2 per cent swing from Labour to the Conservatives. Allowing for the redistribution of constituencies, that would almost certainly result in a hung Parliament, but with Labour as the largest party. However, this does take the Conservatives halfway to an election victory. If the Conservatives could gain a further 5 per cent on election day in three or four years’ time, they would presumably form the next government.

That improvement is the justification of Mr Cameron’s broad strategy, and of the party’s democratic choice of Mr Cameron as leader. His liberal Conservatism appeals to the liberal conservative voters who exist in all three parties. They welcome his opposition to the Government’s identity cards, his advocacy of local rather than regional government, his proposals for reform of pensions, health and education, and his concern for the environment. So far, he has managed to gain additional support without straining too far the loyalties of traditional conservatives.

However, Mr Cameron and two of his senior colleagues have made a proper muddle of the issue of Europe, which always has the potential to divide British politics. Mr Cameron himself started it with his ill-judged observations about the UK Independence Party. He said that they were a “bunch of fruitcakes and loonies and closet racists mostly”.

At the 2004 European elections, the UKIP got about 16 per cent and pushed the Lib Dems into fourth place. It won these votes mainly from the Conservatives, and most of them went back to the Conservatives at the 2005 general election. When Mr Cameron talks about fruitcakes, loonies and closet racists, he is describing a million or more Conservative voters at the last election and, he would hope, at the next election too.

The chairman of the Conservative Party, Francis Maude, made things worse on the Today programme. He said of the UKIP that “some people in the party have some pretty unsavoury connections with the far Right, and they would like to return to a world where Britain is all white and Europe doesn’t exist”. Perhaps such people exist — not every member of Mr Maude’s own party is beyond reproach — but this generalised smear is offensive and the voters being smeared largely voted Conservative last May. Most supporters of the UKIP I have met are normal, patriotic democrats, no bad thing.

Mr Cameron then decided, having done his bit to give the UKIP the publicity it badly needed, that he would be wise to shut up. He did not refer at all to Europe in his leader’s speech in Manchester on Saturday. This omission, however, made his speech sound strangely lopsided, since most of his main themes had a European aspect that he did not mention.

Identity cards arise from European policies, as does the regionalisation to which he is so strongly opposed, while the environment is largely a European competence. Even if he did not wish to discuss the European integration, he should have recognised the European limitations on British policymaking. More than half of all our legislation now comes from Europe. Parliament is the rubber stamp for Brussels.

Yesterday Oliver Letwin further stirred these troubled waters. On the BBC Sunday AM programme, Andrew Marr asked him why there had been no reference to Europe in the leader’s speech. Mr Letwin replied that the speech had concentrated on “mainline issues”, clearly implying that Europe is not one. If Europe is not a mainline issue, what is?

No doubt the real motive for avoiding discussion of all European policy is that Europe does not fit the desired image of Mr Cameron’s party. Euroscepticism could be as embarrassing as a striped polyester bow-tie at a Notting Hill party. To some people, the mention of Europe sounds obsessive or old-fashioned. But Conservative Party policy, while it needs a favourable image, cannot merely be a fashion statement. Europe matters because in wide areas Brussels makes the laws for Britain. Mr Cameron understands that perfectly well. Any policy without a European element is only half a policy, if that.

In any case, the European constitution, the grand project that would make Britain a province of a federal European Union, has not disappeared. The European constitution, possibly in an amended form, has the support of Angela Merkel, the German Chancellor, President Chirac and Nicolas Sarkozy, the future leader of the French Right.

The Conservative Party is opposed to European federalism; so is the nation. The EU already has too much power over British policy; we would prefer our own democracy. Mr Cameron asks British voters to trust him on Europe. They certainly cannot trust Tony Blair or Sir Menzies Campbell. Yet the Conservatives signed the Maastricht Treaty, and pushed it through with brutal whipping under John Major. If they are to regain the trust of moderate Eurosceptics, who are among their own voters, they will have to define their European policy in frank terms. Silence on Europe will not be good enough.

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