rtokens: The Labour opposition are now 1-4 favourites , it said .
pos: NNP NNP VBD DT NNS VBD DT JJS PRP VBD VBN IN CD NNS .
tokens: William Hill said the odds were the longest they had been for six months .
ltokens: UK bookmakers William Hill said on Friday they have lengthened the odds of a Conservative victory in the next general election from 9-4 to 5-2 .