Europe is the sleeping giant of British politics. It often suits our leaders not to talk about it. Just when they think the issue is dead, a monster awakes, goes on the rampage, divides their parties and damages them in the eyes of the voters.

It happened to Tony Blair. Now it is happening to David Cameron. Soon, it will happen to Gordon Brown.

When he came to power in 1997, one of Mr Blair's main goals was to end the "us and them" battle between Britain and Europe conceived in Margaret Thatcher's handbag. When pro-Europeans doubted he would take Britain into the single currency, he told them: "Don't worry, I will do it."

But Gordon Brown had other ideas. So did Rupert Murdoch, the Eurosceptic media baron, whose support Mr Blair deemed more important than his European agenda.

How does the Blair balance sheet stand on Europe as he enters the last lap of his premiership? His "positive engagement" strategy has bought Britain a place at the EU's top table without joining the euro, which many thought impossible. Despite the fractures caused by the Iraq war, Britain has helped to prod a reluctant EU on to the right economic track.

Many diplomats and ministers from EU countries attending the two-day summit in Brussels which ended yesterday are puzzled by Mr Blair. They see him as a brilliant politician but don't understand why he didn't use his strong leadership to achieve more on the European stage. "A megastar who couldn't deliver his own agenda on Europe," one EU official told me.

Although Europe is a dormant issue in Britain for now, it will be alive and kicking before the next general election. The ill-starred EU constitution, rejected in the Dutch and French referendums a year ago, will return in some form because rules for a club of 15 can't work effectively for 25 or 27.

That will be bad news for Prime Minister Brown, who will inherit Mr Blair's rash promise of a referendum on the EU constitution. Ministers are already trying to get the Government off that dangerous hook.

A Europe vote would be a huge distraction from Mr Brown's main task - winning a personal mandate from the British people. But the Tories will doubtless pledge a Europe referendum and so it will not be easy for Labour to ditch one.

If Europe's visionaries come up with another grandiose vision, Mr Brown may decide a fight with them is better than trying to sell the unsellable to a sceptical electorate. But it would mean vetoing the new treaty, and political war between Britain and Europe.

Mr Brown is seen in Brussels as more Eurosceptic than Mr Blair. But there are signs that his approach is changing. In an important speech this week, Ed Balls, the Treasury minister and Mr Brown's closest ally, said Britain must be "fully engaged" and "pragmatic" on the EU.

The Chancellor senses the Tories are on the wrong side of the European argument. He can be a bit more positive because Mr Cameron wants to pull his MEPs out of the European People's Party (EPP-DE), the main centre-right and largest group in the European Parliament.

Angela Merkel, Germany's conservative Chancellor and the EU's new star, is happy to break bread with Mr Brown and Mr Blair (as she did over breakfast yesterday) but shuns Mr Cameron, who should be a natural ally. She is bemused by his pledge.

Like Mr Blair on the referendum, Mr Cameron was bounced by our Eurosceptic-dominated press--in this case during the Tory leadership election by a campaign orchestrated by Daniel Hannan, a Tory MEP and Daily Telegraph leader writer who argues Britain should leave the EU.

Mr Cameron has not raised Europe at PMQs since becoming leader. As on immigration and asylum, he wants his party to stop singing the loony tunes that cost it three elections and would rather talk about climate change or the work-life balance. He judges that the "man in the Dog and Duck" will not notice or care if the Tories leave the EPP-DE.

But Mr Cameron may be wrong. Voters don't like divided parties and, whatever he does now, he is likely to provoke a row with one wing of his party. He doesn't want to U-turn but sometimes that is the lesser of two evils.

Mr Cameron regards the EPP as federalist but it would be bizarre to walk away just when sensible centre-right politicians such as Ms Merkel rule the roost. In any case, the Tories already enjoy the freedom to go their own way on policy under the EPP umbrella. So this is all a fuss about nothing.

Tory efforts to form a new centre-right group have fizzled out. If the Tories walk away, they will be marginalised and seen as another bunch of what Mr Cameron called "fruitcakes, loonies and closet racists" in the UKIP. Their bedfellows might be parties with prehistoric attitudes on gay rights, abortion and women, undermining Mr Cameron's sterling efforts to show his party is changing.

When it came to the crunch, Mr Blair put his domestic priorities ahead of his European goals. Mr Cameron should do the same. His hardline stance might help him win a Euro election but not a general election.

As one shadow cabinet member told me: "The Daily Telegraph has determined our policies for too long. We've tried it. It doesn't work."

a.grice@independent.co.uk