- Written by Jonathan Walker
His battle against media mogul Rupert Murdoch's empire began in 2006 - when he helped to force Tony Blair out of office.
Mr Watson (Lab West Bromwich East) quit his job as a Government Minister and signed a letter demanding that Mr Blair leave Downing Street.
He feared that the former Prime Minister was determined to cling on to power, despite his growing unpopularity. And working with Labour colleagues such as Khalid Mahmood (Lab Perry Barr) and Sion Simon, the former MP for Erdington, he succeeded in forcing Mr Blair to promise to quit within 12 months.
But Mr Watson had created a powerful enemy. Rebekah Brooks, the Chief Executive of News International, was editor of The Sun at the time - and she was a supporter of Tony Blair.
In a speech to the annual conference of the GMB last month, Mr Watson explained what happened next.
"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."
Mr Watson found himself targeted, with strangers going through his bins and harassing his family.
"When the neighbours complained that this time their bins had also been gone through, my family was at breaking point."
"And when our three-year-old hid behind the sofa because there was another nasty man at the door, I snapped."
By this time, he had rejoined the Government as a Minister under the new Prime Minister, Gordon Brown.
But he quit his post - and decided to fight back against the Murdoch empire.
"I stood up in Parliament and for the first time I told the truth that dare not speak its name - that we were scared. that the whole of British politics had been terrified into silence. Become complicit in a cover up of the illegal methods of a corporate beast that was out of control."
Mr Watson joined the Commons Culture, Media and Sport Select Committee, where he was able to quiz executives from News International - the business behind the Sun and the News of the World - as well as Andy Coulson, the former News of the World editor who at that time was Director of Communications for the Conservative Party.
In an interview with The Birmingham Post in April, Mr Watson said he believed the public would be disgusted when it became clear that victims of phone hacking included not just politicians and celebrities but also victims of crime and their families. As we know, he was soon proved right.
He said: "I know of people whose children had their phones hacked. I know of people, there are victims of crime whose family members suffered criminal invasions of their privacy."
He added: "I think a lot of people involved in this case would like to convince you and your readers it is only big name politicians and well known celebrities that are the target of phone hacking.
"Actually, the thing that turns my stomach is private citizens, who are only in the news because they are victims of crime, and there appears to be quite strong evidence to show that their loved ones have had their phones tapped."
Many people in the public eye have suffered invasions of privacy at the hands of the tabloids. In some cases they have taken their tormentors to court and won.
But never before has a politician fought the media and scored type of overwhelming victory enjoyed by Mr Watson today.