David Cameron finally turns on Andy Coulson

A week ago David Cameron described Andy Coulson as "a friend" and insisted he would be a "pretty unpleasant sort of person" if he turned on his former aide.

Yesterday in the House of Commons, Mr Cameron went further than he has before in suggesting for the first time that Mr Coulson may have lied not just to him – but also to Parliament and a court.

Mr Cameron told MPs that Mr Coulson had been appointed Downing Street's director of communications on the basis of "assurances he gave me that he did not know about the phone hacking".

But he added: "He gave those self-same assurances to the police, to a select committee and under oath to a court of law. If it turns out he lied, it won't just be that he shouldn't have been in government, it will be that he should be prosecuted."

Mr Cameron faced fresh questions about why aides had not passed on allegations to him that News of the World had employed a corrupt investigator while Mr Coulson was editor.