David Cameron will become “a laughing stock across the world” if he gives ministers a free vote in the EU referendum, according to Lord Heseltine, the Conservative former deputy prime minister.

The pro-European grandee said if Cameron gave in to pressure to suspend collective cabinet responsibility during the referendum campaign, he would split the Conservative party in a way that could result in it being forced from office.

But Owen Paterson, the Conservative former environment secretary, disagreed, saying a free vote would allow the party to reunite after the referendum to get on with implementing its manifesto commitments.

The issue of whether or not Cameron will allow his ministers to campaign openly to leave the EU while remaining in office has come to the fore after he signalled at the end of last week that the referendum could be held in the summer of 2016.

All sides broadly accept Cameron’s insistence that while the government is still negotiating new terms of membership with the EU, ministers should be obliged to support the prime minister’s strategy.

But, with a deal expected by February, Tory Eurosceptics believe at that point Cameron should suspend collective government responsibility on this issue so that ministers who want to campaign to leave can do so without having to resign from the government.

In the past Cameron has suggested that, if the government as a whole backs the in campaign, ministers should be forced to support that position too. But, with several cabinet ministers and other junior ministers minded to back the out campaign, Cameron may find the prospect of mass resignations makes it impossible for him to avoid allowing a free vote.

Heseltine told BBC Radio 4’s Today programme on Monday that this would be a grave mistake. “[Allowing a free vote] would be to make the prime minister a laughing stock across the world,” he said.

He said that insisting on the suspension of collective cabinet responsibility would be “grossly unfair” to Cameron, particularly given what he had achieved in getting the Tories back in power. And he mocked the idea that it would be possible for cabinet ministers to campaign on different sides in the referendum and to then work together amicably afterwards.

“To have a civil war within the Conservative party at that time, in the belief that the referendum having been determined, the participants in the civil war are going to sit around the table and happily smile together, is, I think, rather naive,” he said.



Heseltine also claimed that Harold Wilson’s decision to allow Labour ministers a free vote during the referendum on membership of the EEC in 1975 “split the Labour party” and helped to keep it out of office for years.

“The consequence was that we had the winter of discontent that helped to keep Labour out of power. It kept the Labour party out of power for nearly two decades,” he said.

But Paterson, one of the most senior figures in the party openly calling for an out vote, said Cameron could not expect some of his Eurosceptic cabinet ministers to publicly back the in campaign with any sincerity.

“Once [the deal] is presented to the people – considering how incredibly thin the prime minister’s demands are and what he’s likely to be granted by the other 27 [EU member states] – it would be wholly incredible for some figures in the cabinet to campaign for that,” Paterson told Today.

He said it was important to allow a free vote so that cabinet ministers could “come together” afterwards and get on with implementing Conservative policies. “Of course we have the horror of a batty, Marxist-lurching Labour party as an alternative. So we have a real responsibility to the British nation to come together again after the referendum to carry on governing.”

In a separate interview, Graham Brady, chair of the Conservative backbench 1922 committee, told the same programme that it was essential that Cameron allowed ministers a free vote.

“Given the scale of the issue, the importance of it, the fact so many ministerial colleagues have spent decades campaigning on it, I don’t think anyone could possibly believe it if they were all corralled into holding a line that they clearly didn’t all believe in,” he said.