A political battle erupted over the London mayoral elections on Tuesday, after a Brownite pressure group launched a ferocious attack on Boris Johnson, the likely Tory candidate. Mr Johnson responded by accusing Ken Livingstone, the Labour incumbent, of “desperation”.

Compass, a left-of-centre group, issued a dossier on Mr Johnson, using extracts from the high-profile MP’s journalistic features and political speeches to brand him as a rightwing candidate. The group argued that Mr Johnson’s bumbling public persona, honed through chat show appearances, masked Thatcherite views that conflicted with the modernising, softer stance adopted by David Cameron.