Ken Clarke filmed ridiculing Tory candidates in off-air chat with Sir Malcolm Rifkind

Former chancellor Ken Clarke and former foreign and defence secretary Sir Malcolm Rifkind have been filmed ridiculing the candidates running in the Conservative leadership election.

The two party heavyweights traded insults in a candid chat while off-air - but on mic and in front of the camera - at Sky News' studio in Westminster on the day Tory MPs vote for their preferred candidate behind closed doors.

Michael Gove is painted as a war-monger, Andrea Leadsom guilty of saying some "extremely stupid things" and not really in favour of leaving the EU, while Theresa May is described as a "bloody difficult woman" who "doesn't know much about foreign affairs" in the remarkable recorded exchange.

Clarke jokes that Michael Gove would take 'Britain to war with at least three countries at once' if elected Prime Minister. Credit: PA

The conversation begins with the pair both hoping Michael Gove fails to earn enough support from fellow party MPs to become one of the two candidates offered to party members.

Sir Malcolm begins the exchange by saying: "I don't mind who wins as long as Gove comes third. As long as Gove doesn't come in the final two I don't mind what happens."

Mr Clarke agrees, saying: "I don't think the membership will vote for Gove. I remember being in a discussion about something to do with somewhere like Syria or Iraq and he was so wild that I remember exchanging looks with Liam Fox. We were exchanging views and Liam was raising eyebrows.

The pair question whether Andrea Leadsom's public support for a Brexit contrasts with her personal belief. Credit: PA

"I think with Michael as prime minister we'd go to war with at least three countries at once. He did us all a favour by getting rid of Boris. The idea of Boris as prime minister is ridiculous."

Pro-Remain Mr Clarke then doubted Ms Leadsom's Leave stance in the referendum, saying: "I don't think either Andrea Leadsom or Boris Johnson actually are in favour of leaving the European Union."

Mr Rifkind responded: "Well I don't think they even cared very much either way."

Mr Clarke added: "She is not one of the tiny band of lunatics who think we can have a sort of glorious economic future outside the single market. So long as she understands that she's not to deliver on some of the extremely stupid things she's been saying."

Theresa May's knowledge of foreign affairs is doubted by Ken Clarke. Credit: PA

Mr Clarke also talked down frontrunner Theresa May, saying: "Theresa is a bloody difficult woman but you and I worked with Margaret Thatcher".

He then goes on to give an endorsement of sorts to Mrs May, saying: "I get on all right with her ... and she is good."

But he then adds: "She's been at the Home Office far too long, so I only know in detail what her views are on the Home Office. She doesn't know much about foreign affairs."

Outside candidates Liam Fox and Stephen Crabb's leadership credentials do not appear to have been discussed by the pair off-air.

Both veterans of the political media circuit appeared to discuss their opinions on the party's leadership race on the record.