Boris Johnson has urged David Cameron to hire right-wing political strategist Lynton Crosby and give him a free hand to run the Conservatives' 2015 General Election campaign.

The Mayor of London insisted Mr Crosby was "by no means as right wing" as many people thought and said the Tories should "break the piggy bank" to secure the services of the sought-after adviser.

Mr Crosby, an Australian who ran both Mr Johnson's campaigns for the mayoralty, is seen as a potentially divisive figure for the Coalition who would distance the Tories from their Liberal Democrat partners.

He is closely associated in Westminster with the Tories' 2005 campaign when then leader Michael Howard focused on crime and immigration and took the party to a third successive defeat.

But his appointment would hearten many Conservatives concerned about a perceived lack of focus in Number 10.

"I think Lynton is a great campaign manager. I think the Tory Party would be mad not to get him," Mr Johnson said.

"They should kill the fatted calf, break the piggy bank, go for Lynton and give him a pretty free hand to run things.

"He would be demonised by the media as some sort of attack dog. He's the soul of sweetness. He's by no means as right wing as everybody will say."

His comments came after he addressed the 1922 Committee of backbench Conservative MPs in the House of Commons.