Some of Britain’s most successful and eminent business leaders have accused Eurosceptic MPs of putting “politics before economics” and abandoning the national interest in their calls for Britain to leave the European Union.

In a letter to The Independent, the group issues a trenchant riposte to politicians who have argued that Britain’s economic interest would be better served outside the EU. They also call for David Cameron to “strengthen and deepen” the European single market to boost Britain’s economy by £110bn. The letter, which is signed by senior figures including the current and next presidents of the Confederation of British Industry (CBI) as well as the chairmen of BT, Deloitte, Lloyds and Centrica, is the first co-ordinated response from the business community to increasing anti-European political rhetoric.

It reflects growing concern in the City that anti-European feeling is not being effectively countered by mainstream political leaders in the wake of last month’s local council elections.

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Two cabinet ministers have already publicly stated that they would vote to leave the EU if a referendum were held today, while privately some senior Tories believe Mr Cameron will never be able to negotiate a new deal for Britain’s membership that Eurosceptics could willingly sign up to.

But in their letter the businessmen write that on a purely economic basis, exiting the EU would be deeply damaging to Britain. “The economic case to stay in the EU is overwhelming,” they say. “To Britain, membership is estimated to be worth between £31bn and £92bn per year in income gains, or between £1,200 to £3,500 for every household.

“What we should now be doing is fighting hard to deliver a more competitive Europe, to combat the criticism of those that champion our departure. We should push to strengthen and deepen the Single Market to include digital, energy, transport and telecoms, which could boost Britain’s GDP by £110bn.”

Addressing concerns that European banking legislation is adversely affecting the City of London, the 19 business leaders say that the right answer is to fight for Britain’s interests inside the EU – rather than attempting to go it alone. “The City of London is Europe’s global financial centre,” they say. “Some of the EU’s ideas such as a cap on bankers’ bonuses put this standing at risk. So the Government needs to work hard to protect it.

“But there is also a huge opportunity to promote London’s capital markets to help solve the problems of the EU banking system. We should promote the cause of EU membership as well as defend our position.”

They conclude: “The benefits of membership overwhelmingly outweigh the costs, and to suggest otherwise is putting politics before economics.”

Some businessmen privately express concerns that were Britain to leave and place restrictions on foreign workers, other European countries would retaliate and make it harder for Britons to work in the EU.

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As well as UK nationals, this may also affect bankers from around the world who are drawn to London as Europe’s financial hub. Should bankers working in London need separate work permits to operate elsewhere in Europe, they argue, this could force many large multinationals to relocate their headquarters. “I don’t think a lot of people have really thought through the consequences of what leaving might mean,” said one.

Meanwhile, the former Foreign Secretary, Lord Howe, said Mr Cameron had “opened a Pandora’s box” by promising to re-negotiate Britain’s membership of the EU and put it to a vote in 2017.

Lord Howe said the Tory leadership was “running scared” of its backbenchers and had allowed Euroscepticism to “infect the very soul of the party”.

“Sadly, by making it clear in January that he opposes the current terms of UK membership of the EU, the Prime Minister has opened a Pandora’s box politically and seems to be losing control of his party in the process,” he wrote in The Observer.

But the Health Secretary, Jeremy Hunt, insisted that the Tory party was “absolutely united” on the issue of Europe and Lord Howe’s views did not “represent the reality” of the situation. “If you look at the substance of the issue, the Conservative Party is absolutely united,” he told the BBC. “Of course we have a debate. Patriotism runs deep in the veins of all Conservatives and when you have an issue of sovereignty it’s something we debate fiercely.”

But the former Labour cabinet minister Lord Mandelson attacked Ukip, which he described as the “UK isolation party”, and the “provisional wing” of the Conservatives, for forcing Mr Cameron into making his referendum promise. “They are saying do what we want, give us what we are demanding or we are going to burn your home down,” he said. “In my view the Prime Minister has got to say enough is enough, you guys have got to clear off, take your tanks off my lawn, I am going to lead this party and govern this country in the way that serves its true economic national interest.”

Making the case for Europe: key signatories

Dame Helen Alexander

One of the few women at the top of British business, Dame Helen spent 23 years with the Economist Group, helping to turn its flagship magazine into a global success selling more than 1.3 million copies a week. She has sat on the board of Rolls-Royce as well as becoming the first female president of the CBI. She is chairwoman of the media and events company UBM.

Sir Roger Carr

The chairman of energy giant Centrica, which has been criticised for hikes in gas bills, Sir Roger lambasted leaders of some British companies last year for greed and forgetting fairness. He was chairman of Cadbury when it was taken over by American giant Kraft and is reportedly in line to become the next chairman of the defence company BAE Systems.

Sir Nigel Sheinwald

The non-executive director of oil giant Shell is a former diplomat who served as ambassador to Washington. He was credited with negotiating the release of 15 Royal Navy personnel held captive by the Iranians in 2007. He also helped broker Tony Blair’s controversial “Deal in the Desert” with the former Libyan dictator Muammar Gaddafi.

Sir Andrew Cahn

A career civil servant and Whitehall mandarin until 2011, Sir Andrew left his role as head of UK Trade and Investment to join Japanese bank Nomura as well as acting as an adviser to controversial Chinese electronics company Huawei. He hit the headlines in 2011 when a leaked email suggested he was seeking ways for the Foreign Office to overcome an underspend by spending more.