Right-wing academic John Marks has joined former education minister Bob Dunn and Sir Robert Balchin, godfather of the grant-maintained movement, in the campaign.

They are part of a 20-strong group, chaired by education spokesman John Bercow. It will advise the party on the case for grammar, secondary modern, high and upper schools.

Mr Bercow wans to name Labour MPs who send their children to grammars and said: “There is no hiding for those people who speak with forked tongue.” The group has already named Labour ministers who went to a grammar school.

The list includes Foreign Secretary Robin Cook, Northern Ireland Secretary Peter Mandelson and London mayoral hopeful Frank Dobson.

Grammar schools in Barnet, Kent, Ripon, Sutton and Trafford are under threat from parental ballots.