FORMER Welsh secretary Stephen Crabb has officially launched his campaign to succeed David Cameron as Conservative Party leader and Prime Minister.

The Preseli Pembrokeshire MP served as Welsh secretary from July 2014 until March this year, when he was handed the job of work and pensions secretary following the resignation of Iain Duncan Smith.

Mr Crabb officially launched his bid in London, where he conceded he was the “underdog” in a race also likely to feature Brexit campaign frontman Boris Johnson and home secretary Theresa May.

"Today we face a set of challenges the like of which we have never seen in Britain,” he said. “A set of problems of almost mind-boggling complexity.

"There is no playbook available that would explain all the manoeuvres and steps that need to be taken to get through this.

“There is no manual waiting on anyone's shelf to be dusted down that provides instructions on the way forward.

"There is certainly no candidate in this race who can stand here today and provide all the answers."

He said controlling immigration would be a “red line” in negotiating the UK’s exit from the European Union, saying “The one message that came through louder than any other in the vote last week is that the British people want to control immigration.”

He added ensuring the UK maintains close economic links with Europe while stopping what he called “the supremacy of EU law” should also be top priorities.

"No-one pretends that this will be anything other than very difficult, but these are the three driving principles that give us the best chance of delivering on the instructions given to us,” he said.

"Brexit needs to do what it says on the tin."

Born in Inverness but raised in Haverfordwest, Mr Crabb has made much of his humble upbringing. His father began claiming long-term sickness benefit before he was born and his parents split up when he was eight years old.

Mr Crabb has said his mother raised him and his two brothers on a council estate with a modest income from benefits and occasional part time work.

Backing him is business secretary and MP for Bromsgrove in Worcestershire Sajid Javid, who many have tipped for George Osborne’s current job as chancellor if Mr Crabb wins the leadership.