Breaking the News: Tom Watson's tenacity played vital role in bringing Murdoch press to account

IT HAS been an astonishing - and unpre- dicted - reversal of fortunes for the politician whose previous claims to fame were his early adoption of social networking and an ill-fated attempt to get rid of Tony Blair.

As a whip then junior defence minister in the Blair government, Tom Watson resigned as part of a failed Brown putsch. Under Brown, he quietly re-emerged as parliamentary secretary at the cabinet office. How things change.

Today he makes headlines across the world. The question currently vexing the irrepressible gossips of Westminster is this: when they are casting the film of the UK's Watergate, which matinee idol will get to play the chunky, bespectacled MP for East Bromwich?

When Watson first got the Murdoch bit between his teeth, it looked personal. The bad blood dates back to 2006, when Watson was the most senior of 15 signatories to a Gordon Brown-inspired letter calling for Tony Blair's resignation. In the end it was Watson who resigned, quickly, before the PM could hoof him out.

In fact Blair struggled on for another year. In the febrile atmosphere of his last months in power, Watson's card was marked by a powerful enemy. As he told the GMB union conference last month: "I was told then that Rebekah Brooks, then the editor of the Sun, now the chief executive of News International, would never forgive me for what I did to her Tony. They said she would pursue me for the rest of my life. She did, they have, I can tell you from personal experience it's not very nice.

"And when you're faced with that daily fear, you really only have two choices. Give in and get out, or give as good as you get."

When the Sun came for Watson, it was ugly. In April 2009, after rejoining Brown's front bench, the paper accused him of being part of Labour spin doctor Damien McBride's email smear campaign against senior Tories. A caricature ran with the tagline: "Mad dog was trained to maul". The paper's former political editor called him a "liar" and the words of a deputy political editor, he recalled recently, were "so harsh and so untrue" that he burst into tears.

The story also appeared in the Mail on Sunday. It was, he said recently, "the worst week of his life": "When the neighbours complained that this time their bins had also been gone through, my family was at breaking point. When our three-year-old hid behind the sofa because there was another nasty man at the door, I snapped.

"The stress was immense. We'd got a new baby. I'd got a young boy. You think: how do I protect my family, there are these people at the door, we're not safe in our home. That week I seriously thought about standing down from parliament and having a quieter life."

Unfortunately for the Murdochs, he decided to stay and front it up. He sued both papers and was awarded "substantial" libel and damages in the High Court. Working on the basis that revenge can be a magnificent but slowly-cooked main course as well as a delicious quick appetiser, he also joined the House of Commons Culture, Media and Sport Select Committee and got to work.

In those early days, Watson was a lone voice. The phone hacking scandal had been rumbling in the background since News of the World royal reporter Clive Goodman and private investigator Glenn Mulcaire were arrested in 2006. By 2009, when Watson joined the select committee, repeated prodding by the Guardian had identified a much wider circle of potential victims, including John Prescott, Max Clifford and Alex Ferguson. The paper also revealed that the News of the World had paid three people more than 1 million in compensation in out-of-court settlements for hacking their voicemails, with secrecy clauses as part of the deal.

This was the opportunity the select committee had been waiting for, to reopen its inquiry into privacy and libel issues. Its subsequent report criticised News International but, despite Watson's constant fanning, the story failed to burst into flames. News International's sister titles, and other tabloids with less than blameless records, were reluctant to give the findings extensive coverage. Fellow MPs, having watched Watson's bins being raked while his children cried - to say nothing of seeing what happened to the Labour Party when the Sun switched its support to David Cameron - were unwilling to get behind his campaign.

Undaunted, he wrote letters, poked sticks and generally refused to let the issue lie down and sleep. He worried away at the unanswered questions: why did the police not interview other senior News of the World journalists, or search their computers, after Mulcaire and Goodman's arrest? Why did they fail to notify all the people whose names appeared in Mulcaire's papers? How did News International manage to secretly pay off other victims? And, with an eye on Murdoch's American interests, especially Fox News, did the News of the World hack the victims of 9/11?

The moment the story turned - when it was revealed that, at the height of a murder investigation the News of the World had accessed missing teenager Milly Dowler's mobile - it was Watson who broke it to the House of Commons. "In the last few minutes, it has just been revealed by the Guardian newspaper that Milly Dowler's phone was hacked by private investigators working for News of the World," he told his Westminster colleagues.

"The company [the News of the World] subsequently revealed the information to the Surrey police who were investigating the matter. As well as being a despicable and evil act that will shock parents up and down the land to the very core, it also strongly suggests that parliament was misled in the press standards inquiry held by the select committee in 2010."

Just two weeks later, the News of the World is no more and the seemingly invincible Brooks is at home trawling how-to-change-careers.com. News International's share price is in the toilet, the company has withdrawn its bid for BSkyB and the FBI are investigating claims that 9/11 victims' phones were hacked.

Now, with Rupert and James Maxwell due to appear in front of the culture and media select committee on Tuesday, Watson smells fresh blood.

James has, he says, "questions to answer" about authorising payments to hacking victims. "The focus of attention will be on him and his corporate leadership of the company," Watson said on Friday. Can he add a Murdoch scalp to his already impressive collection? On his current performance, anything seems possible.