Betting giants William Hill and Betfred have seen Mr Corbyn’s odds shorten dramatically in the last 24 hours

Labour leader candidate Jeremy Corbyn has received crucial backing from Britain’s largest union.

Unite’s Executive Committee voted to give their support to the veteran Islington North MP, who is running for leader of the Labour party.

Traditionally Labour’s largest financial backer, the committee’s 63 members voted on Sunday to back Mr Corbyn, and Andy Burnham, who remains the favourite to win, as second preference.

A spokesperson for Unite said: “The backing for Jeremy Corbyn was in recognition that his policies were most closely aligned with those of Unite.”

Mr Corbyn has run his campaign for the Labour leadership on an anti-austerity platform and famously opposed the Iraq War and has also been endorsed by Britain’s largest transport union, the RMT; the train drivers’ union, Aslef; the Fire Brigades Union (FBU) and the Bakers, Food and Allied Workers Union (BFAWU).

In response to his union support Mr Corbyn said: “Trade unions are a force for good, a force for prosperity and we should listen to them more. For Labour to win again it must show it is on the side of the majority.”

Unite’s backing of Mr Corbyn has solidified his betting odds. Both William Hill and Betfred have seen a consistent shortening of odds from 16-1 to now 8-1 in the last 24 hours.

Graham Sharp, media relations director for William Hill said “One notable thing about leadership contests like this is that the early favourite doesn’t always win. I wouldn’t rule Jeremy out in this contest.”

Peter Spencer, from Betfred, agreed “It’s a pretty phenomenal achievement in 24 hours, which is clearly linked to the huge endorsement he’s received from Unite. I also think that the events in Greece and the moving to the left-wing side of things there has made people here get behind Corbyn.”