Political pedigree: Veteran left-winger
Michael Meacher is one of Labour's longest serving MPs, having first been elected in 1970.
Until he was sacked as environment minister in 2003, he was Labour's most experienced minister, having served in various roles throughout the Wilson and Callaghan administrations in the 1970s.
The zenith of his career, however, came during Labour's opposition years when he sat in the shadow cabinet for 14 years and was tipped by some as a possible future leader.
Formerly a close political colleague of Tony Benn, he stood as the left's candidate against Roy Hattersley for the deputy leadership of the Labour Party in 1983, but was soundly defeated.
Former Labour leader Neil Kinnock once described Mr Meacher as Tony Benn's "vicar on earth".
Mr Kinnock could not bear the left-wing firebrand and only despised him more when he moved away from his old mentor.
But Mr Meacher kept on getting elected to the shadow cabinet by Labour MPs and, under the rules of the day, Mr Kinnock could not sack him.
Only once Labour was elected to office did the leader have the right to form his own Cabinet.
And Mr Kinnock made no bones about the fact that, minutes after entering Downing Street, he would reshuffle the team which had been dumped on him - and out would go Mr Meacher, among others.
But the Oldham West MP proved remarkably resilient. He survived into government under Tony Blair's leadership when Mr Kinnock did not, and was even given a job by Mr Blair, who took a much more charitable view of him.
He moved closer to the political centre-ground after being made environment minister in 1997, though he remained one of the most radical members of Mr Blair's government.
He had several brushes with the press - and was accused of hypocrisy in 1999 for suggesting a ban on owning a second home, at a time when he had three properties.
In 1988 he lost a libel action against the journalist Alan Watkins, who reported that Mr Meacher had invented his working-class roots, by referring to his father as a farm labourer, when in fact he was an accountant.
As an environment minister he was credited as a skilled negotiator and with helping John Prescott in securing the Kyoto agreement to limit carbon emissions in 1997.
But he has rediscovered his left-wing fervour since his return to the backbenches, attacking the government's record on the environment, foreign affairs and Trident.
He has become an outspoken critic of the war in Iraq, despite voting for it in March 2003 - something he says he now "bitterly" regrets.
"That is the biggest political mistake I've made in my life. I believed what the prime minister said about weapons of mass destruction."
He has criticised Chancellor Gordon Brown, the favourite to take over from Mr Blair, for signalling he would renew Britain's nuclear weapons system.
Announcing his intention to stand for Labour leader, he was asked about an article he wrote in 2003, in which questioned why the US authorities were slow to react to warnings of a terrorist threat ahead of 11 September 2001 and why military jets were not scrambled faster.
"I do not believe conspiracy theories. I am not a conspiracy theorist," he
"I do believe the American people, and particularly the widows of those
killed, are entitled to answers to these questions."
Mr Meacher, as part of an agreement with fellow left-wing Labour MP John McDonnell, agreed to step aside after failing to get enough Labour MPs backing him to be able to enter the full leadership contest. Mr McDonnell still failed to get the 44 backers needed so there was no left-wing challenger to Gordon Brown in the official contest.