Downing Street communications chief Andy Coulson has quit after admitting the News of the World phone-hacking row was making his job impossible.
In a personal statement issued by Number 10, Mr Coulson said the drip-drip of claims about illegal eavesdropping under his editorship meant he could not "give the 110% needed"."I stand by what I've said about those events but when the spokesman needs a spokesman it's time to move on," he added.
The Prime Minister said he was "very sorry" that Mr Coulson felt "compelled" to go after months of intense pressure, insisting he was being "punished for the same offence twice".
But critics insisted the resignation was "long overdue", and questioned Mr Cameron's judgment in recruiting the former journalist in the first place.
The timing also sparked accusations that the Government was trying to "bury bad news" while Tony Blair was appearing at the Iraq Inquiry, and with the furore over shadow chancellor Alan Johnson's departure still raging.