Andy Coulson's decision to resign as Downing Street's communications chief was "long overdue", according to the MP who instigated an investigation into the News of the World phone hacking row by the parliamentary sleaze watchdog.
Labour former minister Chris Bryant said Mr Coulson's appointment showed a "fundamental lack of judgment" by David Cameron.
Mr Bryant said he hoped the police would now conduct a thorough investigation into the phone hacking allegations.
He said today: "To say this is long overdue is an understatement. Andy Coulson should never have been appointed in the first place.
"His appointment shows a fundamental lack of judgment by the Prime Minister. Cameron has clung on to him for dear life, long past the point when it became clear that Coulson's position was untenable.
"It is one thing to use Coulson in opposition, but to put him on the taxpayer's payroll at considerable expense and at the heart of Government shows that Cameron is completely unscrupulous.
"Cameron's Downing Street is not as pure as the Prime Minister would have us believe. It's not new politics, it's the oldest tricks in the book.
"I hope now finally that the police will be able to conduct the full, transparent, and thorough inquiry into phone hacking that we are still waiting for and that the murky truth will come to light."
An investigation into claims that MPs' mobiles were hacked by News of the World reporters during Mr Coulson's time as the paper's editor was launched by the powerful Standards and Privileges Committee last year following a request by Mr Bryant.