Mr Davey used to find plenty of the wow factor at Nottingham high, the private school where he was head boy.

Sitting in his constituency office in Surbiton, he recalls an impressive list of the activities he enjoyed at school, including rugby, chess, football and the debating club.

He said school provided a much-needed escape from an otherwise distressing childhood. His father died when he was four, but left money so that he and his two older brothers could attend Nottingham high.

Mr Davey’s mother, who worked briefly as a teacher, later developed a long-term illness. He helped to care for her at home after lessons, but she died when he was just 15.

“I went through a fairly traumatic time as a young teenager and school was quite a stable part of my life,” he said.

“I’m not sure it dealt with a pupil losing his parents terribly well, but one or two teachers made an effort and there was a good community atmosphere.”

Mr Davey is now patron of the Jigsaw 4 Kids charity, which supports children who have experienced trauma.

He is passionate about improving pastoral care in schools, and grows angry when he describes how teachers appear to be losing these responsibilities because of the new salary regime.

His willingness to show his feelings over policies is seen as an unusual trait by some party activists.

“He’s quite red-blooded - for a Liberal Democrat,” said one. “He gets so involved, sometimes he can tie himself up in knots.”

Most colleagues, though, are more flattering. Phil Willis, his predecessor as education spokesman, said he recommended Mr Davey for his sharp intellect.

Mr Davey joined the party as an economics adviser after graduating with a first from Oxford in philosophy, politics and economics, and helped to develop its now-abandoned pledge to put a penny on income tax for education.

Like David Cameron, his Conservative opposite number, he is touted as a possible modernising party leader and is expected to squeeze a lot of publicity from his education brief.

Mr Davey is keen to retain many of his party’s existing policies, including the pledges to cut primary class sizes and ensure all pupils are taught by an appropriately trained teacher.

He stands by the party’s plan to replace A-levels with a Tomlinson-style overarching diploma. But he sees room for improvement on discipline, an area where the Lib-Dems appeared weak at the election.

He recently married a lawyer who specialises in antisocial behaviour issues and will urge delegates at the Lib-Dem party conference later this month to vote for a new package of discipline-related policies.

Ideas Mr Davey is exploring include encouraging schools to call in parents earlier when there are concerns, and to adopt house systems and mixed-year tutor sets.

Mr Davey brushed shoulders with several senior Labour figures before becoming the Lib-Dem education spokesman.

He met Ruth Kelly, the Education Secretary, at meetings of a progressive think-tank before either became MPs.

At school, he lent his history A-level notes to a younger pupil called Ed Balls, who went on to become one of Gordon Brown’s most trusted advisers.

And Mr Davey still goes for occasional dinners with his university politics tutor, Andrew Adonis, who left the Liberal party and is now a Labour peer and schools minister.

Mr Davey disagrees with Lord Adonis over privately sponsored academies, but believes his tutor’s heart is in the right place: “He may have some of the wrong policies, but I wouldn’t doubt his good intentions.”

Barry Sheerman, Labour MP for Huddersfield and chairman of the education select committee, said he had been impressed by Mr Davey’s first speeches on schools.

“He’s going to be a useful addition to the debate on education,” Mr Sheerman said. “He’s refreshingly less dogmatic than his predecessor, and much less long-winded.”

* michael.shaw@tes.co.uk