William Hill has Jeremy Corbyn as favourite to win the Labour leadership race

Top UK Bookmaker William Hill has Jeremy Corbyn as favourite to win the Labour leadership race, they have Mr Corbyn 11/8 favourite, ahead of Mr Burnham on 6/4, Ms Cooper on 5/2 and Liz Kendall on 50/1.

William Hill Bookies spokesman, Mr Rupert Adams said: “Jeremy Corbyn is the favourite and this gamble has resulted in the biggest price fall in political betting history.”

The UK bookmaker said: “Some people may still be refusing to take Stormin’ Corbyn seriously but the punters and the pollsters certainly are.”

Jeremy Corbyn’s Labour leadership race received a mega boost after he gained the backing of UNISON, Britain’s second-biggest trade union.

The general secretary of UNISON, Dave Prentis, said Mr Corbyn’s message had “resonated with public sector workers” and that “their choice shows a clear need for change towards a fairer society”.

UNISON was expected by most people to back Labour’s Yvette Cooper, instead they named her as its second choice candidate. The decision was made by a 23-strong National Labour Link Committee, “following a thorough consultation with all the regions”, it said.

Over 28,000 Unison members are also members Labour party whilst a further 15,000 have signed up as supporters to be eligible to vote in the leadership contest.