The normally brusque Education Secretary opened up during a fringe meeting that at times felt more like an edition of This is Your Life.

It may have been a specially prepared introductory film that softened up the Cabinet’s most famous bruiser, who was able to sit back and enjoy political pundits assessing his qualities.

Some compliments were a little backhanded. One lobby correspondent said he was “a bit of an intellectual thug”. But there was a glowing testimony from Neil Kinnock. The former Labour party leader described his one-time chief of staff as “ebullient, gutsy, very brave, innovative and politically astute”, not to mention being “a gargantuan consumer”.

“Over-eating and drinking too much is a bad thing I wish I didn’t do,” said Mr Clarke during the candid question-and-answer session that followed. “I think it is nervous reaction.”

He also revealed he had tried smoking cannabis after leaving school but found he “couldn’t stand it” and did not experiment further during his university years.

Asked whether he was the “poshest member of the cabinet” Mr Clarke, a head boy at Highgate school, Cambridge graduate and the son of a permanent secretary at the Treasury, said he tried to hide the fact.

He pleaded guilty to being ambitious but refused to be drawn on whether he would end up as a successor to Tony Blair.

A suggestion that Labour was in crisis made him smile. He said today’s problems were nothing compared it to the 1980s when the party had been closer to extinction than many had realised.

Defecting to the SDP was never an option, but he had considered joining the Communist party in the early 70s.

Mr Clarke said his biggest quarrel today was not with the Conservatives but with people who encouraged an anti-political culture in British life. These included civil servants who believed they knew best and ran the country, academics whose theories took no account of reality and media people who thought they had a wonderful independent vision and that all politicians were venal characters.