Cameron challenged on MP’s backing for rival at by-election

Labour has called on David Cameron to withdraw the Conservative whip from an MP who was filmed apparently admitting that he had encouraged a rival candidate in a crucial by-election.

Chris Heaton-Harris, who is managing the Conservative campaign for the Corby poll, was forced to apologise after a Greenpeace activist recorded him revealing that he suggested his friend James Delingpole should stand on an anti-wind farm ticket.

Labour’s vice-chair Michael Dugher said that the Conservative leader’s failure to discipline the Daventry MP for a “serious betrayal of his party” stood in stark contrast to the decision to suspend the whip from Mid-Bedfordshire MP Nadine Dorries after she flew to Australia to appear in I’m A Celebrity Get Me Out Of Here.

Tomorrow’s Corby by-election, triggered by the resignation of Tory MP Louise Mensch, will be a key test of public opinion, with Labour hopeful of snatching back the seat which it held until 2010.

Mr Delingpole, a climate sceptic, announced his intention to stand, but withdrew from the race two weeks ago the day after Conservative energy minister John Hayes controversially spoke out against onshore wind farms.

Speaking to a Greenpeace activist posing as a wind power opponent last month, Mr Heaton-Harris said: “There’s a bit of strategy behind what’s going on.

“I’m running the Corby by-election for the Tories... And Delingpole, who is my constituent, and a very good friend... put his head above the parapet but won’t put his deposit down... It’s just part of the plan.”

During another slightly garbled exchange, Mr Heaton-Harris seems to confess that he put Mr Delingpole up to the stunt.

Mr Dugher said: “Even the Tory campaign manager doesn’t think people should be supporting the Conservative candidate.

“If Chris Heaton-Harris doesn’t have faith in the Tory candidate and his party, the public shouldn’t.”

He called on Mr Cameron “to show some leadership” and act on “a serious betrayal of his party”.