David Cameron unites with Sadiq Khan in call to stay in EU

Weeks after he accused London's mayor Sadiq Khan of being too close to extremists, David Cameron has joined forces with the Labour politician to call for a vote to remain in the European Union.

The two men unveiled a five-point pledge card promising that a Remain vote would guarantee full access to the EU’s single market; workers’ rights protection; the retention of the European arrest warrant; a special status for the UK in Europe; and economic stability.

The prime minister was unstinting in his praise for Mr Khan, portraying the rise of a bus driver’s son to become mayor of London as exemplary of Britain’s openness as a society.

“In one generation someone who’s a proud Muslim, a proud Brit and a proud Londoner can become mayor of the greatest city on Earth. That says something about our country. There are still glass ceilings we have got to smash.

“There’s still discrimination we have got to fight. I’m proud to be here with the mayor of London – with the Labour mayor of London – on this vital issue,” Mr Cameron said.

Labour leader Jeremy Corbyn and Alan Johnson, who is leading Labour's referendum campaign, have both ruled out sharing a platform with Mr Cameron.

The prime minister’s appearance with a leading Labour politician came as the Conservatives’ internal disagreement over the referendum continued to become harsher in tone.

Former minister Ken Clarke, an enthusiastic pro-European, compared former London mayor Boris Johnson to Donald Trump, accusing him of using the campaign to stoke anti-immigrant feeling.

“I think Boris and Donald Trump should go away for a bit and enjoy themselves and not get in the way of the serious issues that modern countries in the 21st century face. He’s a much nicer version of Donald Trump but the campaign’s remarkably similar in my opinion and about as relevant to the real problems the public face,” Mr Clarke told the BBC.

Mr Johnson and justice minister Michael Gove, who is also backing Brexit, on Sunday said Mr Cameron's promise to reduce annual immigration to the tens of thousands was "corrosive" of trust in politics because it could not be fulfilled as long as Britain remains in the EU.

Three Conservative MPs have called for a leadership challenge against Mr Cameron after the referendum, regardless of whether Britain votes to remain in the EU or to leave. Nadine Dorries, Andrew Bridgen and Bill Cash all belong to the wilder right-wing fringe of the Conservatives but their intervention reflects a growing bitterness within the party as the referendum campaign becomes more heated.

Campaigning in Cumbria on Monday, Northern Ireland secretary Theresa Villiers, who is backing Brexit, complained that "we've got the establishment lining up against us". Ukip MEP Mike Hookem pointed to an official postal voting pack distributed in Bristol, which included a graphic showing a pencil poised above the Remain box on a ballot paper.

“It shows a wider problem with this referendum debate which is that people expect the establishment to use whatever tools at their disposal to get the result they want,” he said.