Gordon Brown must do more to appeal to Labour's working class voters if he is to win the next general election, according to the Fabian Society.

In a report published on Thursday the think tank said the prime minister needed to create a "political vision" in order to beat the Conservatives.

The paper - which is timed to coincide with what would have been a November 1 election, had Brown decided to go to the country - comes as the Tories launch a critical poster campaign with the slogan "today has been cancelled".

And recommending that Labour set out a "progressive manifesto", the left-leaning Fabians warned that the party must mobilise its core working class supporters and "disillusioned liberals" in marginal seats.

They said that Labour should spend £4bn on eradicating child poverty to get the targets back on track, review identity cards as part of a "bonfire" of civil liberty infringements and press ahead with green taxes and road pricing.

Other policy commitments in the "bolder Labour vision" should include a referendum on parliamentary electoral reform and a diplomatic solution on Iran, the document said.

Fabian Society general secretary Sunder Katwala said: "Brown's initial positive appeal was built on leadership, competence and authenticity.

"But political vision is central to the authentic Gordon Brown. The message to his advisers should be 'let Gordon be Gordon' - and that must mean letting Gordon be Labour, too."