By Ian Dunt Follow @IanDunt
A letter by former News of the World royal correspondent Clive Goodman has seemingly crippled News International's defence and dragged phone-hacking back onto the front pages.
The Clive Goodman letter, which was written four years ago but only published now, says that phone-hacking was "widely discussed" at editorial meetings at the newspaper until former editor Andy Coulson banned people from mentioning it.
That allegation calls into question Mr Coulson's assertions that he knew nothing of how widespread phone-hacking was until much later.
It emerged that News International redacted all references to the editorial meetings before handing the letters to the media committee.
The new evidence also suggests that Mr Goodman was paid considerably more by News International than it had previously admitted, a fact critics will seize on as evidence that it was paying "hush money" to buy his silence.
"Clive Goodman's letter is the most significant piece of evidence that has been revealed so far," Labour MP and phone-hacking campaigner Tom Watson told the Guardian.
"It completely removes News International's defence. This is one of the largest cover-ups I have seen in my lifetime."
The development comes on the same day that MPs on the media committee announced they would be recalling Tom Crone and Colin Myler, two former senior News International figures who have questioned James Murdoch's version of events at his recent select committee grilling.
The letter also alleges that Mr Coulson offered Mr Goodman the chance to keep his job if he did not implicate the newspaper in court. That allegation raises issues about whether News International deliberately tried to misdirect the legal process.
"Tom Crone and the editor promised on many occasions that I could come back to a job at the newspaper if I did not implicate the paper or any of its staff in my mitigation plea. I did not, and I expect the paper to honour its promise to me," Mr Goodman wrote in an appeal against his dismissal at the newspaper.
The new development is potentially devastating for Mr Coulson and, through him, David Cameron, who offered the former News of the World editor a job as his chief of communications despite knowing about the phone-hacking allegations.
Labour leader Ed Miliband commented: "The prime minister took no action and looked the other way amid these allegations that he had brought someone aware of criminal activity into 10 Downing Street.
"Every new bit of evidence shows how catastrophic his judgement was."
They also cast a spotlight on Les Hilton, Rupert Murdoch's right-hand man, who received the letter but took no further action. Later, Mr Hilton would give evidence before a parliamentary committee insisting Mr Coulson knew nothing about phone-hacking.
While the letter seems extremely serious for News International, it was written when Mr Goodman was fighting for his livelihood and could therefore contain inaccuracies or implied threats.
The new batch of documents, some from the Guardian and the rest from the culture, media and sport committee, also contains letters from News International's legal firm, Harbottle and Lewis, which stress that the Murdochs should not have relied on its review to be satisfied that phone-hacking was not widespread.
The legal firm stated that its review was "short, limited in terms of access to documents, without any access at all to witnesses".
In a devastating broadside against the Murdoch empire, the respected city law firm wrote: "There was absolutely no question of the firm being asked to provide News International with a clean bill of health which it could deploy years later in wholly different contexts for wholly different purposes.
"If the firm had initially been given a retainer as broad as instructions 'to find out what the hell was going on' or (to put it more formally) to undertake an investigation which News International could use for broader purposes, such as laying it before parliament as independent support for the 'one rogue reporter' theory, the firm would have refused the instructions."
News International's parent company said in a statement: "News Corporation's board has set up a management and standards committee, chaired by independent chairman Lord Grabiner, which is co-operating fully with the Metropolitan police and is facilitating their investigation into illegal voicemail interception at the News of the World and related issues.
"We recognise the seriousness of materials disclosed to the police and parliament and are committed to working in a constructive and open way with all the relevant authorities."