PROFILE: Elizabeth Truss

Cue for some predictable Norfolk jokes. One Tory blogger claimed the natives were "so incompetent that they can't use Google". This was not surprising, added another, "given that they still point at aeroplanes in the sky".

A fortnight ago the prospects looked very different for Truss. The London councillor stood on the brink of a starring role in a future Tory government when she was selected resoundingly as prospective parliamentary candidate for the Norfolk association. But within hours there was local uproar when a Sunday newspaper recounted her past indiscretion under the headline "Cameron cutie who had affair with top Tory wins plum seat".

The story was three years old but evidently had not percolated to the quiet market town of Swaffham, where the regional Tories convene. The association was inundated with calls from members angry that Truss and Tory Central Office had kept them in the dark about this "skeleton in the cupboard".

By all accounts the affair began in 2004 when Truss, who had forsworn her membership of the Liberal Democrats to become a Tory activist, was sent to work for Mark Field, the MP for the Cities of London and Westminster. Field, then the Tory spokesman for London, agreed to act as her mentor. A senior Tory was quoted as saying: "It seems Mark took his mentoring duties more seriously than intended."

Truss had been married for four years to Hugh O'Leary, an accountant, with whom she lived in Greenwich. Field had been married for 10 years to his wife, Michele, a former investment banker who became chief executive of the charity Fight for Sight. They had no children.

Field, the Oxford-educated son of an army major, told friends that his affair with Truss ended in 2005. When Truss gave birth nine months later to a daughter, the rumour mill churned. However, she informed friends that the baby was her husband's. Her marriage endured and a second daughter was born to the couple.

The Fields divorced in 2006 - the year a tabloid first revealed the affair. By then Field was the party's spokesman on culture, media and sport, but the scandal was said to have cost him his job in a reshuffle. Field is not close to Cameron. "It is believed there was bad blood between the two because Field stitched Cameron up over a particular seat that Cameron tried for," said a Westminster correspondent.

In 2007 Field married Victoria Elphicke, a celebrity agent, and the couple have a son. To all intents and purposes, Field and Truss had put the affair behind them. "I'm sorry about the affair - it was a mistake," Truss told the Eastern Daily Press. "The main person I am sorry to is my husband. We have now made that up and moved on." Truss insisted that "party officials knew about it", but when pressed about the South West Norfolk association, she replied: "I assumed people knew about it." She added that "in the selection process a rule is that candidates are not allowed to talk to constituency officers".

By her own admission, Truss had no previous links with Norfolk. She was therefore perhaps unaware that the local association had an unfortunate history of candidate selection. In 1987 it chose Baroness (Gillian) Shephard in a rerun after the initial choice of a male barrister from Oxfordshire caused a revolt in its ranks. In 2004 the favourite to succeed Shephard, Nick Hurd, was beaten by Christopher Fraser, who is now stepping down after revelations that he had claimed a second home allowance on his property in Norfolk.

At all events, a torrent of abuse fell on senior Tories and Truss. "This woman is quite obviously a career politician and one of Dave's lovelies," wrote one blogger. An indignant association member said: "If the committee were told of her indiscretion in the past it would have been fine, but it was this blatant secrecy. Do they take us for complete idiots in Norfolk?"

It was an unwise question to ask during a blogging blizzard. When a Norfolk female Tory disdainfully contrasted "what passes for decency in the Notting Hill set" with the "proper standards" found in the county, a wag replied that unless the locals were "totally dissimilar from the rest of the human race", then their "proper standards" consisted of "shagging indiscriminately" and not being found out.

The association's defiance puts Cameron's authority on the line. The Tory leader had commended Truss to the constituency as "an excellent candidate" and recently urged the association to back her - apparently on pain of suspending it. Mutinous muttering includes talk of fielding an independent candidate to "give 'em a bit of a shock". Messages of support are reported to have been sent by neighbouring constituencies, fed up with Central Office "parachuting in the beautiful people".

"Cameron is walking a tightrope," says a political analyst. "He quite likes to define himself against Neanderthal provincials. It helps to demonstrate that the party has changed. However, Truss is not necessarily the best exemplar of his new Tories. Yet he has no choice but to stand by her. So he's on a collision course with the Turnip Taliban."

Truss was born in Leeds, the daughter of a university professor specialising in mathematical logic. "I was brought up in a very left-wing household," she recalled. "My mum was in the CND. All my teachers [at her comprehensive school] were Labour supporters."

Her calls for an education system that places more importance on academic achievement stem from her childhood: "Quite a lot of my ideas came from what I experienced at my school. There was an attitude of defeatism, a lot of lip-service paid to equality but in reality people were slipping through the net."

A bright student, she won a place at Merton College, Oxford, where she studied politics, philosophy and economics.

Alex Wilcox, a former member of the Liberal Democrats' policy committee, recalled Truss in 1993 as "a self-styled radical Liberal Democrat who kept attacking me when I was chair of the Liberal Democrat Youth and Students because I wasn't left-wing enough". He characterised her as "a complete and utter egomaniac pain in the backside, incapable of working in a team". She became president of the university's Liberal Democrats, voicing republican sentiments at the party's 1994 conference. During a debate on the monarchy, she said: "I agree with Paddy Ashdown when he said that everyone should have a chance to be somebody. But only one family has the chance to provide a head of state. I cannot agree with that. We don't believe people should be born to rule."

She later claimed that was a "youthful indiscretion" and she is now said to be promonarchy. Her defection to the Tories left her parents aghast, she said.

After graduating, she joined Shell, rising to commercial manager before becoming head of public affairs for Cable & Wireless. She was also politically active as a Tory, standing unsuccessfully as the Conservative candidate in the West Yorkshire Labour stronghold of Hemsworth in 2001.

Four years later she was pitched into a constituency crisis that must now seem familiar. She was selected by Calder Valley Conservatives from an all-women list (which she claims to oppose) to replace Sue Catling, who was de-selected after allegations of an affair with a former association chairman, which both denied. Catling claimed she had been the victim of a dirty tricks campaign.

Truss lost there, too, leading some to question why an unimpressive record has inspired her inclusion on Cameron's A-list of 100 most promising candidates. She met Cameron only once, she recalled earlier this year, when he came to campaign on her behalf in Calder Valley. "He was education spokesman then and I remember thinking, 'Who is this guy? Couldn't we get someone more well known?'"

Truss must hope that in next week's meeting at Swaffham members heed the charitable view of one Norfolk resident: "Who gives a flying cowpat what sort of romantic shenanigans the woman got up to back then?"