Tom Watson had, over 18 years in parliament, forged a reputation as an immovable force of Labour politics. He was seen as a tireless political machine, who would, some MPs hoped, one day overcome the Jeremy Corbyn project which he occasionally privately mocked.
After all, it was he who was credited with being a factor in Gordon Brown’s mission to get rid of Tony Blair. He took on Rupert Murdoch in the phone-hacking scandal and played a role in the closure of the News of the World newspaper; surely he would be able to finish off the Labour leader, backbenchers would say.
Colleagues believe he has left after too many internal battles with Corbyn’s senior aides. But friends say Watson has found other interests such as public health and has a happy life outside politics. Nevertheless, his departure will force many in the party to reassess their own futures.
Born Thomas Anthony Watson in Sheffield in 1967, he was named after his great-grandfather, a Yorkshire miner. His grandmother, Elsie Watson, was a communist who stayed in the party until the collapse of the Soviet Union.
His parents were both Labour supporters. His father had various odd jobs, as a binman and bread delivery man, until he began a new career in 1970 as a social worker in Kidderminster, where Watson grew up.
In 1984, aged 17, Watson landed a job as in Labour’s headquarters in Walworth Road. Long a music obsessive, he was thrilled in 1987 to help organise Red Wedge, a collaboration with musicians such as Billy Bragg and Paul Weller that sought to draw young people to the party.
After a stint as a union official, Watson entered parliament in 2001 as MP for West Bromwich. He became a whip in 2004 and in 2006 was given a role as defence minister.
Watson was one of many figures in the Labour party who wanted Blair to stand down. But he was one of the few to say so publicly and signed a letter urging Blair to quit.
Brown denied having any part in the plot, which was instrumental in persuading Blair that he needed to announce publicly – as he did – that he would step down as prime minister within the year.
After Brown became prime minister, Watson returned to government as a whip. In 2008 he briefly joined the Cabinet Office, where he was minister for digital engagement and civil service issues.
He was planning to stand down in 2010, friends said, because his marriage was ending. But during a hearing of the digital, culture, media and sport select committee, in which he had taken up a role, a story broke about the News of the World paying out for hacking the telephone of Gordon Taylor, a PFA official.
Over the next few years, he joined the Guardian in pursuing the Murdoch empire, memorably quizzing the medial mogul in front of the Commons’ committee.
Watson enhanced his reputation as a fixer in 2010 when he helped Ed Miliband beat his brother David to become leader of the party. He was rewarded with a job as general election coordinator.
However, he stood down from that role in 2013 following rows over the selection of a Labour candidate for Falkirk, where Karie Murphy, Watson’s then office manager and a close friend of the Unite leader Len McCluskey, was standing.
Since his election as deputy leader in 2015, there has been a war of attrition between Watson and Corbyn’s closest lieutenants, although the men themselves are often said to get on amicably. McCluskey, with whom he had fallen out, has often called for him to be removed for allegedly undermining Corbyn.
Watson’s interests in public health took off last year after he lost 44kg (7st) and reversed his type 2 diabetes.
In his role as Labour’s shadow culture secretary, and as deputy leader, Watson has campaigned against a freewheeling gambling industry, urging a review of online casino licenses and an overhaul of regulations.
However, his instinct for tackling powerful interests came spectacularly unstuck over the claims of historic sexual abuse allegations in Westminster. A report by the former high court judge Sir Richard Henriques into the police investigation into the allegations fabricated by the fantasist Carl Beech said officers may have been put “in a state of panic” by a letter Labour’s deputy leader sent on House of Commons notepaper. Henriques also said Watson “grossly insulted” one suspect who was never charged.
Watson responded by saying the report had been selectively leaked to minimise criticism of the police and that it contained “multiple inaccuracies”.
In September, Corbyn was forced to personally intervene to defuse an attempt by Momentum chair Jon Lansman to oust Watson. The Labour deputy has in recent months become increasingly isolated as allies such as the MP Gloria De Piero and Luciana Berger have left Westminster’s internal Labour battles.