Theresa May, they say, is "on manoeuvres". The Westminster rumour mill is abuzz with the possibility that the Conservative Party might choose a woman leader for the second time in history. That is not something you will hear from May herself, but anyone who followed Wednesday's Prime Minister's Questions will have heard from Ed Miliband, who taunted David Cameron by saying he was looking forward to facing Mrs May across the Despatch Box after the next election. That is when, in Miliband's scenario, he will be Prime Minister and she will be Leader of the Opposition.
David Cameron laughed. So did Philip Hammond, who could be May's main challenger in a future leadership contest, but the Home Secretary glared at Miliband with a look that would pierce an armoured tank.
Unusually for someone who has risen to such prominence in politics, May is a very private person, completely free from the addiction to self-publicity that has been the downfall of so many in her trade. One minister says: "She is pleasant and friendly enough, but incredibly hard work. She has no small talk beyond the most basic stuff." Or, as another put it: "She is extremely impressive in her mastery of the job. But I feel I know nothing about her as a person." That has been the experience of political journalists, too. Last Christmas, she was expected to host a Home Office reception for journalists. She did not turn up.
In the past, this caution gave rise to a suspicion that she was being promoted beyond her ability – the Conservative Party is desperately short of women ministers – but she has laid that idea to rest during her two years as Home Secretary, a post notorious as a graveyard of political ambitions.
May has been confronted with new evidence of chaos at immigration controls, and the farcical mistake in attempting to deport the radical preacher Abu Qatada, and has responded with a mix of steel and stonewalling that has helped her to build respect among colleagues. Civil servants who queried the determination below her courteous exterior were left in no doubt when they saw the speed with which she blamed officials – including the former head of the UK Border Force, Brodie Clark, who denied any liability – for the secret relaxation of passport checks in 2010.
Months later, she had to explain away a basic blunder in calculating when a deadline in the legal battle over Qatada's deportation expired. Summoned to the Commons, she managed to sidestep challenges on the mistake 14 times.
Since then, her popularity has steadily grown on the Tory backbenches and in the offices of right-wing papers increasingly keen to anoint a successor to Cameron. It helped that she blocked the extradition of computer hacker Gary McKinnon to the United States but sent hook-handed preacher Abu Hamza on his way. She has also preached to the Tory converted by tearing into the Human Rights Act. She once teased Kenneth Clarke, then the Justice Secretary, by saying: "I lock them up, you let them out."
And she seems intent on tackling the issue ducked for decades by her predecessors – reforming the pay and conditions of the police service. She betrayed no emotion as she was jeered and heckled by the rank and file at the Police Federation annual conference.
Given that Theresa May has already risen higher in government than any other Tory woman, with one notable exception, and was still in her teens during the rise of Margaret Thatcher, observers have wondered whether she aspires to be the new Iron Lady. She denies having any political role models. Once when she was asked if there was anyone she emulated, she gave the surprising but revealing answer: "I have been a Geoff Boycott fan all my life. It was just that he kind of solidly got on with what he was doing."
The example that inspired her was her exotically named mother, Zaidee Brasier. Her father, Rev Hubert Brasier, an Anglican priest who was killed in a road accident in 1981 when May was in her mid-twenties, scrupulously avoided taking sides in politics to avoid unnecessary dissension in his congregation. The vicar's wife, less inhibited, was an avowed Tory, and instilled the same convictions in their only child.
May's political ambitions formed so early that she has a struggle to remember exactly when she first got actively involved, but it certainly predated Thatcher's leadership. She wanted to be a Tory MP from about the age of 12, and she half-recollects going on the campaign trail during the 1970 general election, when she was 14. She certainly helped during the next election, in February 1974, when she was a 17-year-old sixth former at Wheatley Park Comprehensive, in Oxfordshire, also putting herself forward as the Conservative candidate in the school's mock election. She lost.
Theresa Brasier, as she then was, was also immersed in Conservative politics as a geography student at St Hugh's College, Oxford, where her contemporaries included Pakistan's future prime minister, Benazir Bhutto, who introduced her to Philip May, her future husband. (The couple have no children.) After university, May worked in the Bank of England, and before she was 30 had been elected to Merton council, in south London. She also cut her teeth by contesting a couple of parliamentary seats where there was no hope whatever of a Conservative victory.
There were not many winnable Tory seats on offer in the run-up to the Labour landslide of 1997, but a boundary change created an attractive new constituency in Maidenhead, which drew hopefuls from all around, including Sir George Young, today's Chief Whip, whose family had lived in Maidenhead for 200 years, and Philip Hammond. But May saw them all off with a powerful performance at the selection conference.
In a period when other Tory candidates went out of their way to distance themselves from John Major, who was seen as a loser, she issued one leaflet that said: "Life begins at 40 and Theresa May got her birthday off to a good start when the Prime Minister helped her celebrate …"
She entered a House of Commons where the total number of women had shot up into triple figures through Labour's use of all-women shortlists, but on the Tory side there were just 14 out of 166 MPs, including only five new ones. As the brightest of the five, she was fast-tracked into the job of shadow Education Secretary in June 1998, and has been on the front bench ever since.
Fellow ministers say she is "fantastically hard-working" and "amazingly focused" on the fine detail of policy. Her work ethic has become legendary, with officials swapping anecdotes of her poring through her red boxes until the small hours. Named as one of the ministers who has told George Osborne that there cannot be any more spending cuts in her department, she is said to fight her corner "like a tiger" in Cabinet.
The only occasion in her career when she threw caution away and uttered the words that have stuck with her ever since was at the 2002 Conservative annual conference, when she said: "There's a lot we need to do in this party of ours. Our base is too narrow and so, occasionally, are our sympathies. You know what some people call us – the nasty party."
Those remarks identified her with the modernising wing of the party, three years before the emergence of David Cameron. That, and her more recent support for gay marriage, make her a target of suspicion among Tory diehards who have had enough of coalition and modernisation and want to replay the old tunes of glory.
That could explain why she is reputed to be "obsessed" with hitting David Cameron's target of reducing the immigration figure from more than 200,000 a year to "tens of thousands" a year by the next general election. One official says: "Everything seems to take second place to that – she has moved staff and resources around. She clearly doesn't want to be associated with failure." It also perhaps explains the regular tearoom "surgeries" she holds with Conservative MPs.
One of her allies denies emphatically that the Home Secretary is doing anything that could be construed as disloyal to David Cameron, but there is no doubt that since their drubbing in the Eastleigh by-election, Tories are looking nervously into the future. If they are defeated in 2015, someone will have to pull a shattered party together. Perhaps Theresa May.
A life in brief
Born Theresa Mary Brasier, 1 October 1956, Eastbourne, East Sussex.
Family Daughter of Rev Hubert Brasier and Zaidee Brasier. She married Philip May in 1980.
Education Wheatley Park Comprehensive in Oxfordshire; studied geography at Oxford.
Career First job at the Bank of England, where she was a financial consultant at the Association for Payment Clearing Services, 1985- 1997. Councillor in London borough of Merton, 1986-1994. Elected Conservative MP for Maidenhead in 1997 general election. Has served as Home Secretary since 2010.
She says "I wouldn't use the term boys' club for the Cabinet. I certainly don't feel that I'm out on my own."
They say "I'm looking forward to facing her when they are in opposition." Ed Miliband