The Fabians are losing the battle for the soul of Cameronism to the Thatcherites, according to Sunder Katwala, general secretary of the Fabian Society.
Speaking at the Fabians' New Year Conference, Mr Katwala said: "The Conservatives have changed their image, their language, they say they stand for the things we stand for...They have changed the brand but they don't want to sell out on ideology, for them the smaller state is still more freedom."
David Cameron, he said, was "caught between two audiences" while Cameronism was an "agenda in search of an idea".
"Four years in we don't know who this man is and what he stands for," he added.
Fellow panellist and Guardian columnist Polly Toynbee praised David Cameron's "deftness and charm" but said politicians must be judged by their policies and actions.
Speaking at a debate entitled 'Will the real David Cameron please stand up?' Polly Toynbee said Cameron's green policies had "vanished" and it was Conservative councils which were obstructing wind farms and alternative energy plans.
"It is a party full of climate change deniers," she added.
Cameron's economic policies would have led to a far worse recession than the one we are currently experiencing, she said, and his commitment to localism amounted to "devolving the axe".
His agenda involved "devolving responsibility for paying for things downwards and redistributing money upwards."