No gloating, no complacency, the deal is not yet closed. David Cameron has been repeating this message to his Shadow spokesmen and to journalists before the Conservative conference. The polls suggest he is right to be cautious. This is not false modesty, nor a desire to avoid the triumphalism of Labour's Sheffield rally in 1992, nor suitable restraint at a time of global financial turmoil.

Of course, the Tories are riding high in the polls, above 40 per cent since last autumn. This position has barely been dented by the bounce up to 31 per cent that Labour got in the quickie YouGov poll for The Sun yesterday. The Tories are still on 41 per cent. The conference season is often a volatile period as party ratings fluctuate in response to media exposure.

But there is evidence of some softness in the Tory ratings, not that any of this is of comfort to Labour. The Populus pre-conference poll (for more details see www.populus.co.uk) shows, for instance, that just 56 per cent of Tory supporters say their choice is more a positive vote for the party, while 44 per cent say it is more a vote against the Labour Government. By coincidence, this is the same ratio as for the Liberal Democrats.

However, 81 per cent of the Labour support is positive and only 19 per cent a vote against other parties. This means that 19 points of the 43 per cent Tory rating is a negative anti-Labour vote, that is the whole of its lead over Labour.

This leaves a positive core Tory vote of 24 per cent, against a hardcore Labour vote of about 22per cent.

Moreover, according to Populus, only 28 per cent of voters believe the Tories have really changed under Mr Cameron and “that is why they are doing so much better”. Seventy per cent say the party does not seem to have changed much and is “doing better mainly just because Labour has become so unpopular”.

Similarly, while the Tories have improved their image relative to Labour and are ahead as the best party on five out of nine key issues, their position is not as strong as Tony Blair's new Labour was in the mid-1990s. Tory strategists say that even to get to level-pegging with Labour on the NHS and schools is quite an achievement given their long-term disadvantage here.

The Tories also note that, by 1997, the Major Government had recovered its standing on managing the economy from Labour, though that was on the back of a strong economy and rising prosperity. Now, with the economy heading for recession, the Tories are doing relatively less well than the earlier Labour Opposition.

These findings are a correction to some of the more fanciful predictions about a Tory landslide. As Andrew Cooper, of Populus, has said, there is ample evidence of “a time for a change” mood, but voters are less certain about what they want to change to. Mr Cameron still has to persuade voters about his alternative.

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