By Mark Davies
BBC News Online political reporter
Robin Cook's finest moment in the Commons is generally believed to have come with his devastating analysis of the Scott report on the arms-to-Iraq scandal.
Cook made his reputation as a sharp debater
Just two hours after being handed a copy of the 2,000-page document, the then shadow foreign secretary pulled apart the Tory government's handling of the affair with what was regarded as a bravura performance.
Ironic, then, that after a Cabinet career tinged with disappointment, it is Iraq which has sparked Mr Cook's departure from government.
Some of Mr Cook's enemies regard him as arrogant and distant, while his supporters believe he should have led his party.
What they are all agreed on is that he is one of the Commons' most intelligent MPs and one of its most skilled debaters.
His time in government will also be remembered for the personal problems which dogged him and for his unexpected demotion from the Foreign Office in 2001.
I'm not good- looking enough to be party leader
Indeed, Mr Cook is thought to have believed that his job as foreign secretary was safe after Labour's general election victory that year.
He must have watched the frantic international diplomacy of recent months wishing that he was still in the role now occupied by Jack Straw.
But since being moved to become Leader of the Commons he has been seen as effective in a role he appears to relish, describing it last year as "very rewarding and satisfying".
Mr Cook was born Robert Finlayson Cook on 28 February 1946 at Bellshill, Lanarkshire.
Nicknamed Robin at school, he attended Aberdeen Grammar School before studying English Literature at Edinburgh University.
A councillor in Edinburgh between 1971 and 1974, the passionate horse-racing fan was MP for Edinburgh Central between 1974 and 1983, and is currently MP for Livingston.
He has held frontbench posts for Labour since 1986, when he was appointed as a spokesman on economic affairs, which was followed by a long spell as shadow health secretary.
Demotion from foreign secretary was a surprise
Mr Cook took over the trade and industry brief in 1992 before becoming Mr Blair's foreign affairs spokesman in 1994 - a role he continued as foreign secretary when Labour came to power in 1997.
Under Tony Blair, Mr Cook, once a spokesman of the left-wing of his party, dropped previous commitments to unilateral disarmament and a Eurosceptic approach, and praised the prime minister's "third way".
After high expectations over how he would perform as foreign secretary, he had a rough ride in the role.
He effectively made himself a hostage to fortune by declaring that he would bring an 'ethical dimension' to foreign policy - a vow which often came back to haunt him, particularly after he sanctioned the sale of 16 Hawk jet fighters to Indonesia.
His split and eventual divorce from his wife - with Mr Cook revealing an affair with his secretary to his wife Margaret as they prepared to head off on holiday after a phone call from Downing Street - caused a welter of embarrassing headlines.
His ex-wife wrote a book in which she said of her former husband: "His self-regard was easily punctured and his reaction was protracted and troublesome." Mr Cook responded by saying the book was "vindictive and undignified".
Mr Cook was also seen as having committed a major diplomatic clanger during a trip to India and Pakistan with a suggestion that the UK could mediate in any negotiations over Kashmir.
However, after eventually marrying his mistress, Gaynor Regan, in a secret ceremony, many of Mr Cook's troubles seemed behind him as Labour approached the 2001 general election.
So it was a major surprise when he was demoted to become Leader of the Commons in Tony Blair's post-election reshuffle.
Cook's divorce from wife Margaret was one of the low points
Although his new job represented a step down, Mr Cook proved very comfortable in the role and espoused a commitment to modernisation.
He initiated significant reforms of the House of Commons, with sweeping changes to hours and procedures.
Attempts to reform the House of Lords, however, proved more difficult, while there was an embarrassing defeat on plans to take select committees out of the control of the whips.
Outside government, Mr Cook could prove to a significant thorn in Mr Blair's side, a figure of substance around whom Labour rebels could gather.
For his part, he seems to have long given up hopes of leading his party, once saying: "My looks and personality are very much of the school swot; I'm not good- looking enough to be party leader."
Nor could he have expected to thrive by staying in government and hoping for a Gordon Brown premiership - the two have a bitter rivalry stretching back to the 1970s.