Sitting in the spartan rest room at the Bournemouth convention centre last week, Gordon Brown savoured the cruel trap he had set for David Cameron.

He had just followed up his coup of inviting Baroness Thatcher to No 10 the week before with a conference speech that contained socially conservative platitudes that could have sprung from the lips of William Hague and Michael Howard, the former Tory leaders.

If, by way of response, Cameron scorns the Iron Lady and rejects small “c” conservative values, he stands to lose aspirational working-class voters and alienate a right wing already uneasy about the diluting effects of “liberal” Conservatism. But if the young Tory moderniser shifts course at his own tribal gathering tomorrow to meet Brown by talking tough about immigration and crime, Labour will accuse him of “lurching to the right” or, most heinous of crimes for a contemporary politician, “opportunism”. As if a Labour leader would ever do such a thing.

Just in case the message hadn’t already got through, Brown cited the Iron Lady again to me as he popped out to the conference hall to listen to a cabinet minister: “It was Lady Thatcher, you see, who was the first Conservative leader to insist on attending the whole event. Before her, leaders like Balfour said they would rather listen to their valet than the conference.”

Clearly Brown has been mugging up his history for a purpose. The wooing of the Iron Lady duly worked its magic. Her old colleague Norman Tebbit put the boot into Cameron on Wednesday. Perhaps if Lord Tebbit had attended a fringe meeting on Monday addressed by an old antagonist, Neil Kinnock, the former Labour leader, he might have thought better of it. To a roar from the hall, Kinnock spoke of finally “grinding” the Conservative party “into the dust”.

With a consistent double-digit lead in the polls, senior ministers sitting on tiny majorities may be tempted to join the young turks around the prime minister in clamouring for an election.

When I put it to the prime minister that it is hard to gamble everything on an election after plotting to get the top job for 10 years, Brown just laughed. He threw back my jibe about his being the answer to the Trivial Pursuit question of who was shortest serving prime minister in history, saying that if he calls the election for October 25 he would outlast George Canning, the 19th-century Tory, by a whole day.

The betting is now on November 1 or 8. One scenario has Brown waiting for parliament’s return on Monday, October 8. The following day he announces further troop withdrawals from Iraq. On Wednesday the chancellor brings forward his prebudget report to splurge more money on the National Health Service despite a tight spending round. By Friday Brown calls the election, perhaps toying with the constitutional innovation of giving parliament the right to vote on a dissolution after the weekend, say October 15 or 16. Brown will want to win big to show the exercise was worth it.

Many commentators have dismissed Brown’s keynote speech as dull, but he doesn’t care about that. Let others do excitement: he got the headlines he wanted, not least in The Daily Telegraph which screamed: “Brown targets Tory heartlands”. Sub-Churchillian rhetoric about “this small number of people on this small island” accompanied pledges to crack down on binge drinking and deport foreign drug dealers. As Brown “lurched to the right”, so his ministers staggered after him.

Lynton Crosby, the Australian campaigner who advised Howard in the 2005 election, called this strategy “dog whistling” for right-wing working-class votes. Other classes would not hear the message but those with tattoos would. As one rising and former Blairite minister put it, the Tories are still not “entitled” to themes like this because they need to show they have something new to say. So Labour, despite its highly vulnerable record, stoops to take them up.

Jack Straw, the justice secretary, shamelessly backed a change in the law to support “have-a-go heroes”, opposed by his government in the past for entirely practical reasons. Labour was no longer dog whistling but was shouting “Rover” at the top of its voice. Talk about political cross-dressing; not since Norman Bates donned his mother’s weeds in Psycho has there been a more horrible sight.

Labour’s ugly appeal to inverted snobbery – to judge by the number of ministers’ attacks, Old Etonians should demand protection from the Commission for Equality and Human Rights – also appears to be working. The polls show the Conservative leader out of touch with ordinary people’s concerns. Women voters have also been prised away by Brown’s appeal to authority. His neatly dressed wife Sarah sat docilely through the conference, the very picture of the ideal Tory wife reinforcing the message.

The seriousness of the threat to Cameron is plain, so what can he do? The Conservative leader relishes the role of underdog. When his back was against the wall in the Tory leadership election, he pulled off a blinder of a speech to conference and snatched the prize from the favourite.

Once again he is underestimated by his enemies and there lies hope. As one pollster says, despite the negatives “he is still his party’s greatest asset”. He is fresh, personable and brave.

In the summer when the polls turned against him in the wake of the unnecessary row about grammar schools, he reversed the slide with a series of appearances on television and radio. Yes, it is vital that he makes the clichéd “speech of his life”, but the more he is visible overall, the better his party’s ratings will be.

One close adviser says: “We will be the chasers in any election.” The opinion polls have been volatile all year and Labour as front runner will have to sprint to avoid the accusation of cutting and running because Brown might lose the election a year later.

Time has been Cameron’s worst enemy. The policy reviews conducted over the summer needed to be sifted at leisure to gain maximum impact and provide a suitable policy platform. Undigested, they have added to the confusion about what the Conservatives stand for. The Tory leader also needed time to reassert his authority over his internal critics after the summer squalls. He now has to do it at supersonic speed this week. His tone should be commanding, but not angry.

An emphatic, positive message is needed. Not since 1987 have the Conservatives offered the electorate a glimpse of a hopeful future. Negative campaigning has not worked for them in opposition. Of course they must cover their backs on crime and antisocial behaviour. But these themes should lead from a positive message about how hospitals, schools and the public services can be improved for everyone – Tory cross-dressing on these issues only a few months ago worked. There has been talk of differences between the shadow chancellor George Osborne and Steve Hilton, Cameron’s strategist, about using the “dog whistle.”

It was no accident that the prime minister singled out his experience of the NHS last week. Labour was rattled by Cameron’s praise for the doctors and nurses who looked after his disabled firstborn son. The Tories will offer juicy electoral bribes. These should be secondary to messages about strengthening the family, loosening the grip of Whitehall and offering change.

Cameron has asked himself: to what problem is he the answer? People are more prosperous but they don’t feel at ease. They worry about the social problems of the poor spilling over onto their streets. Hence his talk of a “broken society”. This theme has to be carefully handled so as not to echo the pessimism of which he accuses Brown.

The Tory leader can still see a chink of light. Unite his party this week and he could claw back a few points in the polls. That would present the prime minister with a dilemma. If he does not go for an election now, he will for ever be accused of being “frit”, in Margaret Thatcher’s quaint Lincolnshire term. There is as much at stake for Gordon as there is for Dave as he strides out into the Blackpool spotlight.

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