Now, the BBC reports, he will make it official and announce this evening he is standing down as the MP for Kirkcaldy and Cowdenbeath at the 2015 election. Vince Cable once famously told Brown he had transformed from Stalin to Mr Bean during his time in office - but here are six things he actually did right during nearly two decades in frontline politics.
1. Preventing Britain from joining the euro
Gordon Brown has said he was prepared to quit as chancellor to prevent Britain from adopting the euro as its currency after Labour came to power in 1997. "When I first expressed my doubts about Britain's entry, I stood virtually alone in the Cabinet," he wrote in his memoir, Beyond the Crash. "Indeed, I was ready to resign as chancellor if I was unable to persuade my colleagues of the grave risks of taking us immediately into euro membership."