By Kylie MacLellan
LONDON (Reuters) - Hoping to hold together a party with a small majority in parliament and facing resignations, the British prime minister takes the unusual step of letting members of his cabinet oppose the government ahead of a referendum on Europe.
The year was 1975 and that leader was Labour's Harold Wilson. But with current Conservative Prime Minister David Cameron's plans to hold a referendum on Britain's European Union membership increasingly echoing the last time Britons voted on staying in the bloc, it could just as easily be 2016.
Facing the prospect of members of his team quitting, Cameron used the same tactic as Wilson this month and bowed to pressure to allow ministers to campaign to leave the EU after he renegotiates Britain's relationship with the bloc.
But Cameron, who like Wilson favors staying in a reformed EU and has been accused by Eurosceptics of seeking insignificant changes in the negotiations, may be mindful of history.
Seven of Wilson's team of 23 senior ministers campaigned to leave what was then the European Economic Community. While Britain voted 67 percent to 33 percent to stay in, Labour split six years later, with four pro-Europeans breaking away to form a new party.
"The divisions did not disappear just because they had had a polite agreement to disagree," said Steven Fielding, professor of political history at the University of Nottingham.
"It got them through the referendum campaign but it didn't alter the situation that there were significant figures in the party who wanted to come out and those who wanted to stay in."
The issue of Europe, which contributed to the downfall of two of Cameron's predecessors, has long divided his party and pressure from his Eurosceptic lawmakers helped prompt a pledge to reform Britain's EU ties and hold a vote by the end of 2017.
Cameron has said he will work hard to get "the best possible deal" in negotiations with the bloc. He hopes to win a deal in February, opening the way for a referendum as early as in June.
Some Conservative Eurosceptics say more than half of Cameron's lawmakers could vote to leave, while several ministers, including Home Secretary Theresa May, Business Secretary Sajid Javid, Work and Pensions Secretary Iain Duncan Smith and House of Commons leader Chris Grayling, are reported by local media to be considering backing an EU exit.
In Cameron's favor is that his party is in a strong political position - it won a majority in a general election last year, confounding pollsters' predictions of a hung parliament, is presiding over a strengthening economy and is facing an opposition in disarray.
The election of veteran left-wing activist Jeremy Corbyn as leader of the main opposition Labour has set off an internal conflict over its identity which some in the party fear could make it unelectable for years.
But Cameron's decision to let ministers air their views and campaign against each other has led to warnings from veteran party figures, including Europhile former finance minister Ken Clarke and former deputy prime minister Michael Heseltine, that it will make it harder to heal rifts.
"To have a civil war within the Conservative Party at that time, in the belief that the referendum having been determined the participants in this civil war are going to sit round table the table and happily smile together is, I think, rather naive," Heseltine told BBC Radio.
"It split the Labour Party ... it kept the Labour Party out of power for nearly two decades," he said. "The divisions, the divisiveness, the bitterness that would flow would actually in my view make the prime minister's position look very difficult."
With Cameron having said he will not seek a third term at the next national election, due in 2020, he may be less worried about that than avoiding a short-term split.
"It is only a temporary device," said the University of Nottingham's Fielding. "The person who is going to be dealing with the consequences, we all imagine, won't be David Cameron."
Cameron has written to ministers setting out the ground rules of what he called "a wholly exceptional arrangement".
They cannot speak out against Britain's EU membership until a renegotiation deal is reached and an official government view decided. Before then, they must not say or do anything to undermine the government's negotiating position, he said.
He also said civil servants - non party-political government employees - would have to back the official position. Dissenting ministers' political advisers could support them, but only in their own time and without using government resources.
The letter did not say how this would be enforced, however.
"If they carry on working for the minister it will be very difficult to separate out what is legitimate work ... from what is campaigning," said Andrew Blick, lecturer in politics and contemporary history at King's College London, adding that social media would also make campaigning harder to control than in 1975.
"Who is going to police it and how are they going to police it? ... There is going to be lots of anonymous briefing going on and that is impossible to police."
While Foreign Secretary Philip Hammond has said he would find opposing the government "a very difficult position to be in", other high-profile names could undermine Cameron's clout in trying to persuade Britons to back staying in the bloc.
An ORB poll published this month showed opposition to the EU was growing in Britain, with 43 percent wanting to leave the EU, 36 percent in favor of staying and 21 percent undecided.
With the undecided stripped out, 54 percent of voters want a British exit, up from 51 percent a year ago, while 46 percent want to stay, down from 49 percent.
Those with the power to sway the outcome include London Mayor Boris Johnson, tipped as a potential successor to Cameron. Polls show Johnson, a Eurosceptic who has not yet said which way he plans to campaign, is a trusted voice on the EU and one of the favorites to lead the 'out' campaign.
A YouGov poll in October showed that voters were more likely to back remaining in the EU if Cameron and Johnson said the renegotiation had been successful and Britain was better off in.
While some 'out' campaigners have said it is a disadvantage to their side that ministers cannot air their views until a deal has been reached, they have still welcomed Cameron's decision.
"It is in the best interests of the country and the Conservative Party and the quality of debate," said lawmaker Steve Baker, co-chairman of Eurosceptic group Conservatives for Britain, adding that Cameron's guidelines made it clear ministers would be "on the shortest possible leash".
"It is not perfectly helpful to the campaign but it is certainly better than the certainty of ministers having to resign if they wish to stand by their convictions," he said.
Baker said it was "unavoidable" that Conservatives would be on opposite sides of the debate from each other.
"We are all absolutely determined that we are going to be in a good shape to govern," he said. "That is a very, very strong binding force which will restrain behavior that would otherwise create irreparable rifts."
(Editing by Pravin Char)