'A burning indignation towards people who abuse power'

With his story on bugs in high places, Nick Davies picks a fight with the big boys

The biggest stories of recent times have all made the same dispiriting revelation – those we think of as moral figureheads are not quite as well-intentioned as we thought. First it was bankers, then MPs, and now, with almost Swiss timing, the press.

It's not the first time the Fourth Estate has come under such scrutiny – only last year Nick Davies published his book Flat Earth News, which levied a barrage of criticism against modern newspaper journalism, claiming it was institutionally corrupt, self-protecting and riddled with "falsehood, distortion and propaganda". So it was no surprise to find Davies's byline over The Guardian's story, on bugging at News International, as it broke on their website on Wednesday evening.

An investigative journalist with more than 30 years' experience, and now 56, Davies has fulfilled an ambition to become an investigative reporter first kindled when he heard of Nixon's resignation at the hands of Woodward and Bernstein. He was then working as a stable-hand, shortly after graduating from Oxford with a PPE degree in 1974.

But his desire to bring to justice those who abuse their positions began much earlier. As a child Davies was energetic and talkative, and, as a consequence, he says, was hit a lot by adults at home and at school. "It left me with a burning indignation towards people who have power and abuse it," he says. "As it turns out I have a job that involves exposing people in power."

He didn't like school, and says he "zigzagged between state and private school in the south-east of England .... The kids at the state schools thought you were posh and at the private schools they thought you were an oik". But even this had its upside, as he says he now feels comfortable talking to anybody.

His journalistic career began with a place on the Mirror's trainee scheme in Plymouth. Two years later he moved to London to join the Sunday People, then a heavyweight investigative newspaper, but the tabloid culture, which Davies recalls as "bullying", didn't suit him, and he fled to the Evening Standard, and the Londoner's Diary gossip column. A year later, diary editor Peter Cole left to become news editor at The Guardian and Davies went too, arriving in July 1979, on the same day as Alan Rusbridger, now the paper's editor-in-chief. He stayed as a reporter for five years, but left after a falling out with then editor Peter Preston. "I felt they were being weak-kneed and they felt I was bolshy and difficult," he explains. He then joined The Observer for a two-year stint as home affairs correspondent. The managing editor was Magnus Linklater, who took him to Robert Maxwell's London Daily News in 1986, making him chief feature writer. When that folded a year later he left for America with his partner, where he wrote his first book, White Lies, the story of the wrong conviction of a black janitor for a white girl's murder.

In 1989 he returned to England and signed a freelance contract with The Guardian, to write 18 stories per year "or the equivalent in time and effort". Although he never has to come into the office, Davies says The Guardian is a civilised place to work. "Nobody interferes, people don't shout at you, it's all terribly civilised. At other papers there is this intense pressure to get exclusive stories. The Sunday Times and the Daily Mail led the way with the use of dark arts. But The Guardian is a sort of well-mannered gentleman."

Davies is universally described as a man who ploughs his own furrow, happiest away from the pack. He has plenty of critics – some describe him as arrogant, others as an egotist. Such criticism is no doubt in part because of Flat Earth News, and in part out of jealousy of his highly enviable contract with The Guardian. The arrangement couldn't suit him better, allowing him freedom to chase stories in great depth from his home in Lewes, Sussex, where he is part of a growing social scene of journalists and writers.

He recently spent nine months investigating the tax affairs of Hans Rausing, a luxury most reporters can only dream of. In his spare time he rides a friend's horse, sometimes cutting a solitary figure across the downs, and is keen on cricket and supports Arsenal.

The coming weeks promise to shed more light on the nitty-gritty of Davies's story, as the Commons Select Committee for Culture, Media and Sport investigates his claims. Rebekah Wade, incoming chief executive of News International, has already written to committee chairman John Whittingdale, accusing The Guardian of "substantially" misleading the public. The Guardian is standing by Davies's story, and Davies himself says "not a single word of our original story is incorrect".

Davies has picked a fight with News International, David Cameron's high command, and potentially the police and the PCC. But if anyone is up to the challenge, it's Davies.