There is something surreal — no, really quite barmy — about the European debate in Britain. Five years after the crash, the economy is still flat on its back. Repair of the nation’s finances has stalled. The health of the neighbouring Eurozone is far from assured and its future shape is unclear. David Cameron’s response? To promise a vote (though not for another five years or so) on British membership of the European Union (EU).

The rest of the world looks on in profound bafflement. The US has felt moved to warn the prime minister that if he takes Britain out of the EU, he will wave goodbye to influence in Washington. In Beijing, last week, I heard Chinese officials express polite bemusement that Britain could detach itself from the world’s most important economic bloc.

Cameron’s much-hyped speech on the subject will settle nothing. It represents an expression of impotence — a cry of pain almost — rather than a strategy. Cameron wants a “new settlement” so Britain can repatriate powers from Brussels, but keep privileged access to the single market. He promises a renegotiation and a referendum to ratify it if he wins the 2015 election.

Yet, the speech is destined to disappoint. It is the place where the irresistible force of rising Tory party europhobia meets the immovable object of geopolitical reality. Britain’s allies, trading partners and investors are promised several years of uncertainty, while Cameron’s Conservatives wrestle with the effort to reconcile the irreconcilable.

The prime minister says he wants to stay in the EU. The, as yet unspecified, opt-outs and concessions he seeks will make Britain “more comfortable” in the union. Yet, on being asked whether Britain will still be a member 10 years hence, the best George Osborne, Chancellor of the Exchequer, offers is that he “hopes” so. For many of the deeply eurosceptic Tory ministers and MPs now driving policy, a referendum is the route to the exit rather than a better deal.

Britain’s partners accept advancing political and economic integration within the Eurozone will necessarily change the relationship. Germany’s Angela Merkel is sympathetic to the idea that single currency “outs” need safeguards to protect their voice in the wider counsels of the union — most obviously in decisions about the single market. As irritated as European leaders often are by British exceptionalism, there is no great continental move to push Cameron out. They may sometimes pretend otherwise, but even the French see advantages in perfidious Albion remaining in the club.

Merkel et al, however, have their own red lines. Britain already has a clutch of “opt-outs”, ranging from the Schengen area of border-free travel to the euro. If Cameron’s price now is repudiation of past commitments and obligations, then it is too high. Sure, there can be talks about social legislation and regional policy, but the unravelling of the union’s core “acquis” — or accumulated legislation — is a bridge even Britain’s best European friends are unwilling to cross.

Grand strategy has never been the prime minister’s forte, but he must understand this. So why the speech? He is held prisoner of fear of a great rupture in his party akin to convulsions about the Corn Laws in the 19th century and imperial trade preferences early in the 20th. Now, as then, an argument about Britain’s place in the world has become enmeshed in a neuralgic Tory debate about national identity and sovereignty.

Britain’s departure from the EU is for now a possibility rather than a probability. Nick Clegg, leader of the Tories’ Liberal Democrat coalition partner, repudiates Cameron’s plan. After a period when it also struck a eurosceptic pose, the Labour party is resisting the temptation to back a referendum. Douglas Alexander, the party’s foreign affairs spokesman, last week described the EU as a vital multiplier of British interests and values. And a Tory majority in 2015 is a far from obvious outcome given the dismal state of the economy.

The UK Independence party, which advocates complete EU withdrawal, adds fuel to the fire of Tory europhobia. However, though they do not much like the EU, voters may prove more pragmatic than what polls suggest. It is one thing to denounce Brussels’ meddling; another to risk prosperity and jobs by pulling up the drawbridge against Britain’s most important trading and investment partners.

The danger is that, in bowing to the populist clamour, Cameron has created a political dynamic that leads to departure, while Europe is being made a scapegoat for Britain’s self-inflicted economic ills. The prime minister’s partners are simply not prepared to see their plans for “more” Europe held to ransom by Britain’s demands for “less” Europe.

The eurosceptics hold Margaret Thatcher as their champion. She was certainly tough on those who imagined the EU’s future as a federal superstate. However, behind the rhetoric, she held on to a hard-headed view of the national interest. She also understood the political nature of the union. Calling for a Yes vote in a 1975 referendum, she said the case for membership rested on Europe’s role in amplifying British power. The EU opened “windows on the world” that otherwise would be closing after the end of the empire.

Even at the height of her confrontation with Jacques Delors, the then European Commission President, Thatcher understood the stark political realities facing a middle-ranking European nation. As she said in her infamous Bruges speech: “Britain does not dream of some cosy, isolated existence on the fringes of the European Community. Our destiny is in Europe, as part of the Community.” There is a sentiment for her self-chosen heirs to reflect on.

— Financial Times