Gordon Brown loved the G20. The group of industrialised nations embodies the former British prime minister's vision of global economic governance, a subject that fascinated him even before the financial crisis. He regards the London G20 summit in April 2009 as the highlight of his three-year premiership, a turning point in the global recession.

With only a week before the general election, the FT interviewed him at his Manchester hotel: Mr Brown talked eagerly about global reforms, bank capital ratios and the Toronto G20 summit, even though the polls told him he would not be attending. His aides dearly wished he would focus on issues closer to home.

On May 6, the opinion polls were borne out and Mr Brown was ousted by David Cameron, the 43-year-old Conservative party leader. Still relatively unknown outside Britain, what contribution will he make to his first G20 summit?