Stephen Crabb, 43, is not what many people would regard as a typical Tory MP.

Born in Inverness, he was raised by his Scottish mother after she became estranged from his violent father. Mr Crabb was eight at the time.

After living in his grandparents’ two-bedroom council house in Greenock, the young Stephen and his two brothers eventually returned to Haverfordwest in Wales with their single mum.

His background means he is a working class Conservative, far removed from the Establishment Tories of the Old Etonian Oxbridge-educated David Cameron and Boris Johnson.

In some ways, Mr Crabb, who was educated at state schools and at Bristol University, represents the unconventional side of modern Conservatism similar to that of Ruth Davidson, who has personally endorsed her Tory colleague as a potential UK party leader.

In a recent interview, he said: “The most powerful thing to me, looking back, is the way that my mother went through a crisis in her life and became welfare dependent.

“She started working just a few hours each week, increasing her hours and then moving to a position where with extra training she was able to move into full-time work, become a car owner, and reach full economic independence.”

Mr Crabb also recalled how he “nicked off school to pick potatoes to buy stuff like trainers”.

After entering Westminster in 2005 as the MP for Preseli Pembrokeshire in Wales, the father-of-two made rapid process up the greasy Whitehall pole. His emollient style won him plaudits where he moved within 18 months from a junior Welsh Office minister to Welsh Secretary.

When Iain Duncan Smith resigned as Work and Pensions Secretary over the proposed cuts to disability benefits, the Prime Minister promoted the rising star, who as a child knew the help welfare could provide to his mother, who struggled to bring up her family singlehandedly on a council estate.

His first speech as Secretary of State saw him tell MPs: “A compassionate and fair welfare system should not just be about numbers. Behind every statistic there is a human being and perhaps sometimes in government we forget that.”

A Christian, he voted against gay marriage.

Mr Crabb has admitted that the Tories got it "massively wrong" when in 1997 they opposed devolution; now he insists the party is at the forefront of embedding devolved powers in Scotland, Wales and across England.

The former marketing consultant will be running on a joint “blue-collar” ticket with fellow Remainer Sajid Javid, the son of a bus driver, who also attended state schools and went to Exeter University.

Their appeal as non-Establishment Tories from a younger generation might just appeal enough to win it among party members, if, and it is a big if, they can first get the support of enough MPs.