On 7 May, Britain could take a decisive step towards leaving the European Union if voters re-elect a Conservative government committed to holding a referendum on the UK’s continued membership of the EU. With polls showing a 50-50 split between those wanting to stay and quit, the prospect of Brexit is more real than at any time since London joined the Brussels-based club over 40 years ago.

Some relish the prospect of saying auf wiedersehen to the UK. In a recent French poll over half said they’d be glad to see the back of Britain. Last year, former French premier Michel Rocard urged “England” to “get out of the European Union before you wreck it.” And some editorialists in Berlin, Paris and elsewhere salivate over the likelihood of London leaving.

Student or retired? Then this plan is for you.

It is easy to understand why many Europeans are fed up with Britain’s half-in, half-out position, the arrogant way in which successive UK leaders have lectured colleagues on how to run their economies and the infantile, incoherent, and irresponsible way the government of British PM David Cameron has sought to renegotiate Britain’s membership terms.

But those praying for Britain to leave the EU should be careful what they wish for.

Firstly, a UK exit would make the Union poorer – Britain is the world’s fifth largest economic power, the biggest destination for foreign investment in the bloc and pays more into the EU’s coffers than it gets back.

Secondly, it would make the EU weaker on the world stage. The 28-member club would lose a nuclear-armed, permanent member of the UN Security Council, which – along with France – is the only other EU country able to protect and project its values by force.

Finally, the departure of free-trading Britain would make the EU more prone to supporting state aid for ailing industries and over-generous subsidies for farmers – two policies that were as wrong when the UK joined the Union in 1973 as they are now.

Those who would like to see the back of Britain, like Rocard, argue that London has “never, ever allowed even the smallest step towards greater integration” - conveniently forgetting that the UK championed the EU’s first major treaty change, the Single European Act.

They paint a picture of the UK as a wrecker – despite it being behind some of the EU’s biggest success stories – such as the single market, the smashing of state monopolies and the enlargement of the EU to extend the Union’s zone of peace and prosperity eastwards.

Let’s not forget that when 10 mainly former communist countries joined the EU in 2004, Britain was one of only three countries to welcome their workers from day one.

True, Britain has opposed many moves towards further EU integration – such as monetary union. But who would seriously argue that the single currency has made citizens in Eurozone states richer and the EU a more cohesive, prosperous club?

Besides, when it comes to actually applying EU laws – rather than calling for new ones to be added – Britain is always near the top of the league table, with Belgium, Italy and other more happy-clappy EU states languishing way behind it. Remember, it was France and Germany that ripped up the Stability and Growth Pact that was meant to police the Eurozone.

Successful relationships are built as much on differences as similarities.

Britain will always stand out from the rest of Europe because of its peculiar geography (an island nation that looks as much to the Atlantic as the continent), its history (a former colonial power not invaded since 1066), its politics (an old democracy that never flirted with fascism or communism) and what former French leader Charles De Gaulle called its “very original habits and traditions” (pragmatists, not philosophers; common, not Roman law.)

But it is also important not to exaggerate Britain’s exceptionalism – as many Tory and Ukip supporters do. Most of the country’s trade is with the EU, not the United States, China or the Commonwealth.

Like most Europeans, Brits believe in free healthcare and schooling and relatively high state spending. On issues like religion, gay marriage, abortion, development aid, global warming, and the death penalty Brits are also much closer to secular, progressive western Europe than the US.

Almost exactly 40 years ago, in June 1975, British voters were asked whether they wanted to remain in the European Economic Community the country had joined two years earlier.

Over two-thirds voted Yes and the UK has remained a grumpy, garrulous but vital and valuable member ever since. It is not just in Britain’s interest that it remains so, but in Europe’s too.

Gareth Harding is Managing Director of Clear Europe, a communications company. He also runs the Missouri School of Journalism's Brussels Programme. Follow him on Twitter @garethharding.