Feature: Battle lines drawn as politicians take sides over British EU membership

The new Battle of Britain moved into full swing Sunday as politicians took sides in opposing campaigns that will decide whether the country should quit the European Union.

It promises to be a roller coaster ride in the run up to June 23 when more than 40 million Britons will vote in a referendum.

Prime Minister David Cameron fired the starting gun in Downing Street by announcing the date, saying "Britain is approaching one of the biggest decisions this country will face in our lifetimes."

He warned leaving Europe would threaten Britain's economic and national security, saying those wanting to quit Europe offered 'risk at a time of uncertainty - a leap in the dark'.

Within minutes members of the main powerhouse in British politics, the Cabinet, split, with six of Cameron's top team saying they back leaving the EU.

Britain's cabinet operates on the principle of collective responsibility, with government ministers expected back the prime minister, or resign.

Cameron, though, is giving his ministers freedom to take support either side.

Already dubbed the 'gang of six' the cabinet members wanting to leave are Work and Pensions Secretary Iain Duncan Smith, Commons Leader Chris Grayling, Culture Secretary John Whittingdale, Northern Ireland Secretary Theresa Villiers, Justice Secretary Michael Gove and the Minister of State for Employment Priti Patel.

Chancellor George Osborne and Home Secretary Theresa May are among the majority of cabinet members joining Cameron in the 'stay' campaign.

Gove, one of Cameron's closest allies, issued a long statement explaining why he wants Britain to leave the EU. Describing how he had been wrestling with the most difficult decision of his political life, Gove said Europe was the one issue where he and Cameron differed.

"It pains me to have to disagree with the Prime Minister on any issue. My instinct is to support him through good times and bad. I believe our country would be freer, fairer and better off outside the EU," he said.

"Our membership of the EU prevents us being able to change huge swathes of law and stops us being able to choose who makes critical decisions which affect all our lives," he added.

Describing the EU as a failure on many fronts, Gove concluded: "This chance may never come again in our lifetimes."

Another of the six, Chris Grayling said: "The EU is holding this country back. We cannot control our borders, limit the number of people who come here, do trade deals. I do not believe we can take decisions in the national interest when we are part of the EU."

Jeremy Corbyn, leader of the main opposition Labor party said changes negotiated by Cameron were largely irrelevant to the problems most people in Britain face, but added Labor will campaign for Britain to stay in Europe.

"That's not because we don't think the EU needs reform. Being part of Europe has brought Britain investment, jobs and protection for workers, consumers and the environment. We are convinced that the EU is a vital framework for European trade and international cooperation in the 21st century," said Corbyn.

Cameron will Monday address the House of Commons, giving MPs a chance to have their say. So far, though, the debating has been restrained.

That will all change soon when the official in and out campaigns are launched. That is when the gloves will be off in the desperate fight to win over the large number of Britons still to make up their minds. Their votes will be decisive. Endit