Sir John Major warns Conservative Eurosceptics to keep quiet or Britain could end up leaving EU PM's decision to promise a referendum is a 'gamble', says Sir John Says Eurosceptics undermining efforts to claw powers back from Brussels Sir John Major: The former Prime Minister has urged Conservative Eurosceptics to keep quiet Sir John Major warned "irreconcilable" Conservative Eurosceptics to keep quiet today as he warned they are undermining David Cameron's attempts to claw back powers from Brussels ahead of an in/out referendum on Britain's EU membership. The former prime minister described Mr Cameron's decision to promise a referendum in 2017 as a "gamble" that could lead to Britain's exit from Europe and warned the issue had "come close to destroying the Conservative Party" in the past. Calling for the Prime Minister to appoint a Cabinet minister as his "lead negotiator" ahead of the referendum, even if it means overruling the Liberal Democrats, Sir John was scathing about Eurosceptic rebel MPs. He said those who believed it was "helpful" for the Prime Minister to receive unsolicited advice about which powers should be repatriated, since it demonstrates to other EU colleagues the strength of feeling in Britain, were "quite wrong." Such advice, given publicly, will undermine the Prime Minister's negotiating position. He will be seen to be acting under political duress, rather than principle and conviction - and his hand will be weakened," Sir John said. In a reference to his own battles with those he infamously described as Eurosceptic "bastards," the former prime minister added: "I know that because I have been there." Speaking at the Chatham House foreign policy think tank in London, Sir John, making a rare intervention into contemporary politics, made a powerful case for Britain staying in the EU having renegotiated a looser, more trade-based relationship with Brussels. He said that on principle, he was not in favour of referendums in a Parliamentary democracy - but suggested Mr Cameron had had no option but to promise one on EU membership after the next election. The Prime Minister delighted Tory MPs last month when he said that if re-elected, he would seek to renegotiate Britain's membership of the EU and then offer voters the first decision on membership since we entered the Common Market in 1975. This referendum could heal many old sores and have a cleansing effect on politics. It will be healthy to let the electorate re-endorse our membership, or pull us out altogether," Sir John said. At present, we are drifting towards - and possibly through - the European exit. We need a renegotiation - and a Referendum endorsement of it. If this is denied, the clamour for it will only grow. But it is a gamble - for the Country and for the Conservative Party. The relationship with Europe has poisoned British politics for too long, distracted Parliament from other issues, and come close to destroying the Conservative Party. It is time to resolve the matter. 'Gamble': Sir John has said David Cameron's decision to promise a referendum in 2017 could lead to Britain's exit from Europe Sir John, who faced a damaging revolt from Conservative MPs over his decision to sign the Maastricht Treaty in the early 1990s, urged today's rebels to give the Prime Minister space to renegotiate Britain's relationship. "We need to prepare our own proposals without delay, and negotiate courteously and with understanding," he said. This manner in which these negotiations are conducted is vital. "If we enter them with the aggressive attitude of "give us our way or we quit," we will fail." Sir John said some polls suggested that currently, voters might vote to leave the EU, and said it would not be "easy" to negotiate a better deal that would satisfy people. Sir John warned that "rebellion is addictive" for some Tory "irreconcilables" who were so obsessed with leaving the EU that they were prepared to "bring down any Prime Minister." "Members with Conservative heads and UKIP hearts cannot be placated," he said. Whatever is offered to them will be insufficient. They will demand more. They will only be satisfied by withdrawal. The Prime Minister should be prepared for the likelihood that the irreconcilable among his Parliamentarians, including ministers, will campaign for a British withdrawal. Defiant: Sir John urged Mr Cameron to begin renegotiation talks soon The former prime minister urged Mr Cameron to defy Liberal Democrat objections and to begin renegotiation talks soon. I believe he should appoint a lead negotiator who sits in the Cabinet. If the Liberal Democrats oppose such an appointment - which is possible, since they oppose the referendum - then the Prime Minister should overrule them. On a matter of this importance, the tail must not wag the dog. Sir John said he did not have a "shred of doubt" that British interests were best served by remaining inside the EU. The tens of thousands of UK companies who trade with the European Union should think long and hard about the consequences of exit. So should their employees, numbered in millions. To leave, would be a jump into a void," he said. It would be a brave decision for Britain to go it alone. I bow to no-one in my pride of our country, but we should see ourselves as others see us. We are 70 million in a world of 7 billion, with nations like China, India, Turkey, Indonesia, Mexico and Russia all rising in economic and political importance. Do we wish to become less relevant in their eyes, or face the future as a leading voice in a block of 500 million people? To leave would be to march against history. Many who wish us to withdraw from Europe do so on the assumption that we could enhance our relationship with existing allies: most obviously, the United States and the Commonwealth. They are mistaken. UKIP Leader Nigel Farage said: "The very fact that Tories are calling out retired PMs to back up their leader shows just how weak David Cameron is. Major's speech simply corroborates the fact that UKIP are the only party who want to get Britain out of the EU. The Tories can scaremonger or try to charm people back all they like - the British voters are more discerning than that.