He'll be back, the hardline Eurosceptic who became an unlikely liberal

Short, bustling and ever-ready with a quote, John Bercow is one of most energetic MPs not just in the Tory party, but in Parliament. Yet it is his personal journey from right-wing ideologue to social liberal that has come to define the Buckingham MP as a leading Conservative moderniser.

Just as Michael Portillo re-invented himself from gung-ho Secretary of State of Defence to a man prepared to mop floors in a hospital, Mr Bercow's allies believe his transition also offers a route-map for the Tory party itself.

In the Eighties, he was a member of the far-right Monday Club and Federation of Conservative Students, a hardline Eurosceptic favourite of Norman Tebbit. But although his views on the euro remain unchanged, almost everything else about John Simon Bercow's policies have. In particular, he has become a passionate advocate of gay rights, voting to lower the homosexual age of consent.

In his New Year address to his local party this year, he warned that the Tories were seen as "racist, sexist, homophobic and anti-youth" and in "worse shape than ever before". The party hierarchy was prepared to overlook his views mainly because he was an excellent debater and parliamentarian, recognised first by William Hague, then Iain Duncan Smith. He regularly spoke at Conservative associations up and down the country, impressing the elderly audiences with his wit and verve.

Never shy to put his own money where his mouth is, when he was looking for a seat to fight he spent £1,000 hiring a helicopter to attend two selection meetings on the same snowy day. Mr Bercow's regular campaigning on equal rights issues led some colleagues to suspect he was gay. But when he addressed a Stonewall fringe meeting at the Tory conference last year, he disappointed his audience by announcing he was in fact, straight.

He became engaged to Sally Illman, 32, a former Labour Party activist who campaigned for Tony Blair in 1997. Ms Illman, who was in the Commons yesterday to stand by her man, supports his decision to resign. They marry next month in the Commons chapel.

Unfortunately, Mr Bercow has had to sell his beloved Home Cottage in his constituency because his fiancée, at 5ft 11ins, kept banging her head on the ceilings.

Mr Bercow was not pleased with his move from shadow Chief Secretary to the Treasury to Work and Pensions minister in a reshuffle this year, but impressed Central Office with his work rate.

The party plans to make use of his hyper-energetic talents as a "key campaign co-ordinator" and he could well return to the Shadow Cabinet. Whether it is under Mr Duncan Smith or another leader remains to be seen.