In tomorrow's New Statesman, Boris Johnson adds his voice to those demanding that Lynton Crosby, the hard-nosed Australian political strategist, be installed as the Tories' campaign chief for the 2015 election. He tells Andrew Gimson, who has profiled Crosby for the issue, that the Tories should do "whatever it takes" to secure the services of the man who oversaw his election - and re-election - as Mayor of London. "Push the boat out, break the piggy bank, kill the fatted calf," he says.

Boris describes Crosby as "an absolutely brilliant campaign manager".

"I’ve never known anyone so good at motivating a campaign." He had "a thing called the pink cardigan", and "all these hordes of young people working for him". At the end of each day, he would throw the pink cardigan to someone who had “monstered the Labour Party or done something particularly distinguished".

As Gimson, the author of Boris: The Rise of Boris Johnson, notes, this is a "rare example of Johnson agreeing with something that Cameron and Osborne want to do." He adds: "The appointment would be popular on the Tory back benches, which assume Crosby would treat the Liberal Democrats far more roughly than Cameron has done. In the mayoral elections, he proved expert at harvesting Lib Dem votes for Johnson."

Yet it is precisely these virtues (in the Tories' eyes) that mean Cameron is wary of recruiting Crosby. The appointment of the man behind the Tories' 2005 "Are you thinking what we're thinking?"campaign would be viewed as an act of wilful provocation by the Lib Dems. The fear in Downing Street is that the arrival of "the Wizard of Oz" would threaten the coalition's fragile truce.