DAVID Cameron was under pressure last night to come clean over plans for a “poisonous” post-election pact with Nigel Farage amid fears it would speed up NHS privatisation.

Labour shadow health minister Andy Burnham challenged the Prime Minister as the Tories cosied up to Ukip in the wake of Thursday’s TV election debate.

In a letter, he said: “Your deal with Ukip is a poisonous proposition that would deny working people the care they rely on from a service they cherish.”