Poll guru to work full time for Tories

As well as bolstering the input from the Australian strategist, the lucrative contract secures polling services from his business partner Mark Textor and support from a team of staff.

The Prime Minister recruited the man credited with Mayor of London Boris Johnson’s ballot box successes last year to work part time on boosting Tory re-election prospects and the new deal signals that the party is shifting its 2015 preparations up a gear.

A senior Tory told the Mail on Sunday: “We are thrilled to have Lynton. Labour hates him because they know he gets results.”

Mr Crosby was closely associated with the Tories’ failed crime and immigration-centred 2005 campaign under Michael Howard, and former deputy party chairman Lord Ashcroft warned that the man known as the “Wizard of Oz” for his multiple successes in Australian elections was a “recipe for... conflict and confusion”.

But Mr Johnson had urged the Prime Minister to “break the piggy bank” to get him on board.

Mr Crosby has since been the focus of intense media scrutiny amid claims that his lobbying firm posed a conflict of interest with his role as a key aide to Mr Cameron.

Conservative party chairman Grant Shapps told The Sunday Times: “This is about ensuring we have the best possible campaign team and operation in place to secure a Conservative win in order that we can continue driving down the deficit, creating more jobs and cleaning up the mess left by years of Labour.”

Labour MP Sheila Gilmore said: “Given the Tories are so keen to talk about the recruitment details of the lobbyist Lynton Crosby, perhaps they would care to finally answer the key questions surrounding his role, questions David Cameron has repeatedly dodged over recent months.”