Profile: Tom Watson, Labour deputy leader
Tom Watson, who has been elected as Labour's deputy leader, has been an MP since 2001.
The 48-year-old served as a minister in the Labour government and had a stint as the party's deputy chairman, garnering a reputation - which he rejects - as a heavyweight political bruiser.
The MP for West Bromwich East is also known as a campaigner, including on historical child abuse and a recent legal challenge to the government's surveillance laws. But his most famous crusade was over phone hacking.
He took one of the starring roles in the interrogation of Rupert and James Murdoch in 2011, as a member of the Commons culture select committee.
'Rebuild the party'
His dogged investigation won plaudits, and he co-wrote an account of his hacking adventure - Dial M for Murdoch - and became a familiar figure on rolling news channels.
He has since pressed for tougher press regulation and for the recommendations of the Leveson Inquiry to be implemented in full.
In the aftermath of his select committee grilling of the Murdochs, he was drafted into Labour leader Ed Miliband's top team as the man charged with organising the troops to secure an overall majority at the next general election.
Mr Watson's record as campaign chief was mixed - the party famously lost safe Bradford West to a resurgent George Galloway but scored other by-election victories along the way.
His downfall came in the wake of a row over trade union influence over Labour candidate selection.
Following Labour's general election defeat, he put himself forward for the job of deputy leader, pledging to "rebuild the party across the UK".
A former trade union official himself, who once shared a flat with Unite leader Len McCluskey, Mr Watson entered Parliament in 2001 as MP for West Bromwich.
After an initial stint in the whips' office, he was sent to the Ministry of Defence, where he was credited with helping secure pardons for soldiers shot for cowardice during World War One.
But in 2006, he resigned as a defence minister, calling for Tony Blair to quit in the interest of the Labour Party and the country - a move that hastened the then prime minister's departure from office.
He was accused of conspiring against Mr Blair with Gordon Brown when it emerged he had visited the then chancellor at his home in North Queensferry, Fife, shortly before stepping down.
Both men denied any plot, but many - inside and outside Labour - did not believe them.
When Gordon Brown took over as leader and prime minister in 2007, Mr Watson was brought back into government as a whip, and in 2008 was appointed minister for digital engagement.
In that role, he found a niche.
Known as an early adopter of social media, he was the first MP to have a blog and has described himself as "an apprentice nerd" for his love of all things technological.
But during this period Mr Watson was accused of being involved in the scandal surrounding a plot by Gordon Brown's spin doctor Damian McBride to spread smears about senior Tories.
Career in brief
- West Bromwich East MP 2001-present
- 2005-06: Government whip
- 2006: Defence minister
- 2007-08: Assistant government whip
- 2008-09: Cabinet Office minister
- 2011-13: Labour deputy chairman
- 2011-2013: Labour elections co-ordinator
- 2015: Labour deputy leader
The Mail on Sunday accused him of "encouraging" Mr McBride while the Sun published a cartoon of him under the headline "Mad dog was trained to maul".
Mr Watson subsequently won "substantial" libel damages from both newspapers in the High Court, which ruled the stories linking him to the plot were not true.
He resigned from his ministerial role in the wake of the McBride row for family reasons, he insisted - he wanted to take a step back from front-line politics and concentrate on his wife and children.
Hoping for what he called "a productive life as a backbencher", he decided to join the culture select committee to pursue his interests in sport and the arts.
But just two days after joining, the Guardian newspaper put phone hacking back on the agenda and the committee decided to investigate it - once again thrusting Mr Watson into the spotlight.
"The first thing News International did was try to have me removed from the committee," he claimed in 2011.
"I realised then that these people were never going away. Something had clearly gone wrong with newspapers and somebody had to get to the truth.
"There weren't many MPs who were prepared to do that for fear of being targeted, so I decided I had to do it.
"People then started coming to me - whistleblowers and victims - and I felt I had a responsibility towards them. I couldn't walk away."
A prolific Tweeter about politics, as well as his latest discoveries in music, film and video games, he managed to squeeze in a mention of little-known blues-rock band, Drenge, in his resignation letter from the job of general election co-ordinator in 2013.
In the letter, Mr Watson, the son of a union official and a social worker, who has two children with estranged wife Siobhan, said it was better for the "future unity" of the Labour Party that he went.
His resignation was prompted by a row over the Falkirk seat being vacated by Labour's Eric Joyce - the Unite union was accused of hijacking the process to select a new candidate to replace him, and Mr Watson's office manager was the union's preferred candidate.
In his letter to Mr Miliband, Mr Watson said he was not quitting because of "unattributed shadow cabinet briefings around the mess in Falkirk... though they don't help".
He said some within the party had still not forgiven him for resigning as defence minister in 2006, but added: "I fully accept the consequences of that decision and genuinely hope my departure allows the party to move on."
As deputy leader, he is now at the forefront of the party's attempts to move on, this time from its general election defeat.