Despite being relegated to the backbenches last December, the arch political fixer has never been far from the thoughts of those at Westminster.

Prior to July's reshuffle, most commentators took the idea of Mr Mandelson becoming Northern Ireland secretary as an elaborate political hoax.

But they knew it would be difficult for the prime minister to resist bringing the former trade secretary back into the cabinet in his second reshuffle of the year, despite it being barely 10 months since Mr Mandelson was forced to leave the government.

Mr Mandelson resigned after The Guardian newspaper revealed details of a secret �373,000 loan between him and the paymaster general Geoffrey Robinson, who also resigned.

The then trade secretary had borrowed the money to buy a �475,000 home in Notting Hill, a fashionable area of west London.

Although his building society ruled out action against him and the house has since been sold, commentators wondered whether the prime minister would dare to bring back the disgraced minister after less than a year.

Mr Mandelson's former Notting Hill home

Tony Blair once claimed his self appointed task of modernising the Labour party would only be complete once the party learned to love Mr Mandelson.

Reaction to his re-emergence at the Northern Ireland Office will show if his fall has made the party rank-and-file any more sympathetic to the so-called "prince of darkness".

Mr Mandelson was born into a Labour family in 1953. His father sold advertising for the Jewish Chronicle and his mother was the daughter of Herbert Morrison, the post-war Labour Cabinet minister.

In his youth in Hendon, he joined the Young Communist League after opposing Labour's support for the United States' intervention in Vietnam.

It was during this period that he attracted the attention of the intelligence service, MI5.

His rapid return from the far left began when he won a place at Oxford. Prior to this, he spent a year working in Tanzania under the aegis of Archbishop Trevor Huddleston, the anti-apartheid campaigner.

Red rose

He began his political career proper through a job at the economics department of the TUC and from there joined Lambeth council, from 1979 to 1982.

Mr Mandelson moved on to become a producer for London Weekend Television, from 1982 to 1985.

His political star started to rise when he became Labour's director of communications from 1985 to 1990 under the then leader Neil Kinnock.

Under his guidance, the party took on a more professional media presentation and dumped the old style red flag as its symbol in favour of a red rose.

Gerald Scarfe depicts the Blair-Mandelson relationship

After being praised for Labour's slick campaign in 1987 he resigned as Labour's director of communications in 1990 to contest the Hartlepool seat, which he won in 1992.

In the same campaign Labour crashed to its fourth successive election defeat.

When John Smith became party leader in the aftermath of Labour's defeat Mr Mandelson he fell out of the limelight.

But, after backing Tony Blair in the leadership race which followed Mr Smith's death in 1994, he again became one of the most important men in the party.

He had earlier supported Gordon Brown as Labour leader and his decision to back Blair led to a rift between himself and the current chancellor.

As the 1997 general election approached, Mr Mandelson moved to the foreground of the parliamentary Labour party via the opposition whips' office and a stint as shadow civil service minister.

Mr Mandelson made it to the Cabinet in 1998

When Labour celebrated its victory, Mr Blair ostentatiously paid tribute to "Bobby" - the campaign code name for Mr Mandelson.

In Labour's first year in government, the prime minister created the position of minister without portfolio for his friend which made the best of his abilities at co-ordinating Labour's media presentation.

When Mr Mandelson was promoted to trade secretary last year, the move was seen as his first real test in a government post where he would have to make difficult decisions with economic and political consequences.

But when it came down to it Mr Mandelson did not always act as always expected.

He backed away from privatising the Post Office and protected the coal industry.

Only on "Fairness at Work" did Mr Mandelson live up to his billing as being more sympathetic to business than the unions when he set out the rules on union recognition.

Dome secretary

Once in government Mr Mandelson was also given responsibility for the Millennium Dome.

He was a strong supporter of the project, seeing it as a chance to emulate his grandfather, who had masterminded the 1951 Festival of Britain.

Mr Mandelson was in charge of the Millennium Dome

But this led to a question mark over how his connections with the Dome and gaining sponsorship for the project might conflict with his role at the DTI.

His impartiality in adjudicating Rupert Murdoch's bid to buy Manchester United was called into question because of his friendship with the Australian media magnate's daughter Elisabeth.

But in the event those decisions were taken out of his hands by his eventual resignation from government.

The political fall out from the secret loan did not end with his and Geoffrey Robinson's resignations but eventually led to the resignation of Gordon Brown's spin doctor Charlie Whelan over the suspicion that he leaked the details of Mr Mandelson's loan to the press.

It was one of the most damaging period's of Labour's administration to date but it must have also personally upset the prime minister to lose one of his closest friends and allies in the Cabinet.

So Mr Blair must be pleased to bring Mr Mandelson back to his frontbench team.

And although prior speculation dismissed the move to the Northern Ireland Office, many will be suggesting who better than the arch fixer to kick start the failing peace process in Northern Ireland.

Mr Blair will be hoping the new Northern Ireland secretary will be able to work the Mandelson magic on the deadlocked political parties.

And it will also be a relief to Mr Blair to have Mr Mandelson back in the Cabinet as the government begins to prepare for the next general election.