As one of Tony Blair's favourite ministers, Dr John Reid worked his way across a string of different government departments before taking the reigns at the Home Office in May 2006.

Described by many as a bruiser - a term he dislikes - but with a strong academic leaning, he has been one of the government's most effective performers over the last decade.

A committed and no-nonsense Blairite, his tone plays well with the tabloids.

Across Whitehall, he has frequently left civil servants in no doubt about who is in charge of his departments.

But his cabinet career is coming to and end as he prepares to step down with Tony Blair.

Background

Hailing from Bellshill, North Lanarkshire and born to mixed-denomination parents - his father was a postman, his mother worked for a brewer – Reid comes from an industrial working-class background.

Leaving school at the age of 16, he first worked as an insurance clerk in Glasgow where he met his first wife Cathie – who later died of a heart attack in 1998.

It wasn't until his mid-20s that he studied for his first degree through an Open University foundation course. He then later continued to study, taking a history doctorate at Stirling University where he wrote a thesis on the 19th century West African slave trade from a Marxist perspective.

Upon leaving university he joined Scottish Labour where he began work as a researcher, but it was to be his grounding in Communist-speak that would lead to his big break on the national scene, after a heated argument in a crowded bar during the 1983 party conference.

Sat with a Labour militant who was denouncing George Robertson for his lack of Marxist zeal over one of the party's wrangles about voting rights, Reid intervened, correcting the man's faulty political grammar.

He informed his opponent that the split within the party was between quasi-Leninists led by Tony Benn and the quasi-soft-left 'Luxemburgers' led by Neil Kinnock.

Later that night Reid found himself taken to Kinnock and told to repeat his remarks. Reid recalled, "Neil got up and shook my hand and said, 'Thank Christ someone else knows what is going on in the party."

Reid then went on to be appointed a full-time aide in Kinnock's private office, writing speeches and looking at reform of the party.

Career

In 1987 Reid became MP for Motherwell North, and in parliament went to work on the shadow defence team.

After boundary changes, Reid returned from the 1997 election with a new constituency of Hamilton North and Bellshill and then in 2005 he took the seat of Airdrie and Shotts with 59 per cent of the vote.

Reid is the only minister to have held eight cabinet posts in seven years - he attended cabinet as transport minister in 1998 before moving on to the posts of secretary of state for Scotland, secretary of state for Northern Ireland (the first Roman Catholic to hold the position), minister without portfolio (Labour Party chairman), leader of the House of Commons, health secretary, defence secretary and home secretary.

Other positions included minister of state for defence (his first post from 1997-98), where he is said to have done an impressive job on Labour's strategic defence review.

Reid was seen as a success in Northern Ireland and as Tony Blair's enforcer as Labour chairman. His rise through the cabinet was also helped through mastery of his briefs - he is seen as having one of the brightest minds in the government.

And it also helped to be a staunch Blair loyalist. He was also one Alistair Campbell's first media weapon of choice.

Reid famously clashed with Jeremy Paxman after he was introduced as a government "attack dog", a description the minister rejected and put down to prejudice about his accent and background.

Reformer

As health secretary, Reid delivered a staunch defence of Labour's reform programme to the party's annual conference - making the case for extending to all the choices available to those who could afford it.

Appointed home secretary in May 2006 - replacing Charles Clarke in the wake of a Home Office scandal involving the release of foreign national prisoners – Reid set the pace by saying that parts of his ministry were not "fit for purpose".

"I'll fucking well work 18 hours a day to sort this out," he vowed.

And his high profile during the security scare over an alleged plot to blow up transatlantic airliners prompted fresh speculation that he was really running the country in the prime minister's absence.

But his announcement that he intends to leave the cabinet is likely to mark the end of a high profile ministerial career.

Now married to Brazilian filmmaker Carine Adler, Dr Reid is an old-fashioned, straightforward political operator - smart and tough.

A former member of the Communist Party, he has been viewed as having a colourful political past - of which he has said: "I used to be a communist. I used to believe in Santa Claus."