Labour figures last night paid tribute to Gordon Brown, as the former prime minister announced he would not seek re-election next year.

Mr Brown, who has served as MP for Kirkcaldy and Cowdenbeath since 2005 and first entered Parliament in 1983, will step down from Westminster after spending the past four years focusing on charity and campaigning work.

But his intervention in the Scottish referendum earlier this year was credited as saving the union between England and Scotland.

Mr Brown had previously expressed unease about Labour running a joint campaign with Conservatives in the poll.

He was also tipped as a potential contender for the Scottish leadership of the Labour Party after former leader Johann Lamont announced her resignation. But he ruled himself out of the contest early on.

Neil Findlay, who urged Mr Brown to stand before announcing his own candidacy, said: “Gordon Brown has made a huge contribution to politics in Scotland and far beyond. His lifelong commitment to tackling poverty has guided his political life.

“I was delighted to speak on the same platform as him during the referendum when he … put the Labour case for remaining part of the UK — a case based on social solidarity and the redistribution of the UK’s resources.”

Labour leader Ed Miliband said Mr Brown had been “a towering political figure for a generation ... He will carry on serving the Labour Party in other ways,” Mr Miliband told the BBC.