Yesterday I joined Ed Miliband as he grilled Cameron in Parliament. We asked why he did not act on a New York Times article from September 2010 which implicated Andy Coulson in the phone-hacking scandal – four months before the Prime Minister’s Director of Communications finally resigned from 10 Downing Street.

The New York Times revealed in September 2010 that “Coulson talked freely with colleagues about the dark arts, including hacking” and how one former-editor had been to “dozens if not hundreds of meetings” with Coulson when the subject came up.

This information made the Met launch Operation Weeting and terminate Neil Wallis’s contract as a public relations advisor. And the allegations completely contradicted Coulson’s claims that he had no knowledge of phone hacking while he was editor of the News of the World.

So, how did David Cameron not know? And why was he not briefed?

Ed Miliband challenged Cameron in Parliament yesterday over why the Prime Minister had failed to act on the facts in front of him.

Cameron admitted that he read the New York Times article. But he simply shrugged off the real question over why he continued to employ Coulson -; saying that there was nothing in the piece which would have led him to change his mind

I did not think this was satisfactory, so I questioned the Prime Minister further. I asked if he read the article himself, who pointed it out to him, and who he discussed it with.

But Cameron continued to dodge the New York Times allegations.

We have the right to expect that Cameron would have made every effort to get to the truth about Mr Coulson -; especially after the New York Times allegations.

But it’s now clear that – at very least – Cameron’s top team created a shroud of secrecy to try to protect the PM from any knowledge of Coulson’s murky past -; and that this intrigue placed Sir Paul Stephenson in a position where he had no choice but to resign on Sunday.

Cameron may now say that with “20 -; 20 hindsight” he would not have employed Andy Coulson. But the Prime Minister’s refusal to listen to the warnings show a great arrogance and lack of judgement.