Cameron feels he is required to show some public contrition

By Tom Bradby: Political Editor

I think David Cameron feels that it is certainly necessary to apologise today and that he is required to show some public contrition.

He's on the hook twice at Downing Street; first of all for employing Andy Coulson in the first place - he had of course resigned as editor of the News of the World.

And secondly for the decision to bring him from opposition to Government as director of communications at a time when Mr Coulson was being asked ever more questions on phone hacking.

That said, the Prime Minister was very careful about what he said.

He was somewhat generous about Mr Coulson under the circumstances - going out of his way to say that he did a good job while he was in here.

I think Mr Cameron's intention is to try and effectively kill this off as a story for him by making that fulsome apology.