GORDON Brown, described as a colossus of British politics, has been praised for his contribution to national life as reports suggest he is preparing to call time on his House of Commons career.

The former Prime Minister is widely expected to announce before Christmas that he is stepping down as an MP at the May general election. His announcement will follow that of his erstwhile colleague Alistair Darling, who after his leadership of the Better Together campaign in the independence contest, announced he would be stepping down as an MP at the election.

While there was no official confirmation from Mr Brown's office, it has been speculated for some time the former premier was unlikely to stand again for Westminster given his international charity commitments.

While having a distinguished career for many years, some will regard his greatest political moment to have come in September when in a series of impassioned speeches he helped the No camp to victory.

Some colleagues had wanted the party's big beast to become leader of the Scottish Labour Party after Johann Lamont's resignation but Mr Brown had insisted he was not going to return to frontline domestic politics.

A colleague said: "Gordon has confirmed to friends that he will stand down at the election in May. He wants to go out on a high after effectively salvaging the campaign to keep the UK together in September. He will focus on his charity work."

Since Labour's 2010 election defeat, the ex-PM has devoted much of his time on raising money for international charities and his role as United Nations special envoy for global education.

The 63-year-old politician has been MP for Kirkcaldy and Cowdenbeath, formerly Dunfermline East, since 1983. He lost out on the Labour leadership to Tony Blair following the death of John Smith but served as chancellor for 10 years before succeeding his colleague from 2007 until 2010.

Appearing on the BBC's Sunday Politics Scotland programme, all three candidates for the Scottish Labour leadership wished Mr Brown well.

Frontrunner Jim Murphy said: "If this is his decision, it's entirely for him to make. All three of us would wish him well with whatever he does next."

MSP Sarah Boyack described Mr Brown as a "colossus" of ­British politics.

Her colleague Neil Findlay said it was no secret he wanted Mr Brown to have put his name forward to lead the Scottish party.

Last night, Mr Brown was unavailable for comment.