Ed Miliband has been elected leader of the British Labour party, defeating older brother David by a wafer-thin majority of 50.65% to 49.35%.
The shadow energy secretary appears to have benefited from a last-minute surge of support before voting in the postal ballot closed on Wednesday.
He was installed as bookies' favourite with less than 24 hours to go after trailing David throughout the four-month contest to find a successor to Gordon Brown.
David won a majority of support from Labour's MPs at Westminster, but crashed to defeat due to Ed's dominance among trade unions and grassroots activists.
Ed secured the crown in the fourth round of counting in Manchester, after the votes of eliminated candidates Diane Abbott, Andy Burnham and Ed Balls were redistributed to take his support past the crucial 50% mark.
He campaigned on a platform of ‘turning the page on New Labour’ and his victory will be seen as a move to the left following the Blair/Brown era.
However, he has rejected opponents' characterisation of him as ‘red Ed’ and is likely to continue to court the centre-ground support which took the party to power in 1997.
Mr Miliband now faces the challenge of restoring Labour's fortunes and mounting a credible challenge to the coalition Government led by David Cameron - as well as the more immediate challenge of delivering his first leader's speech to the party's annual conference in Manchester on Tuesday.