Stormont First Minister Peter Robinson has lifted his threat to resign over the controversy about on-the-run republicans after accepting the terms of a judicial review into the issue announced by the Prime Minister.
The Democratic Unionist leader stepped back from the brink after claiming assurances he had received from the Government about letters sent to more than 180 individuals - advising them they could return to Northern Ireland without fear of prosecution - had rendered them effectively "worthless".
In response to David Cameron's announcement, Mr Robinson said: "I very much welcome the judge-led inquiry that he announced and I am happy with the terms of reference that have since been set out in the Government statement."
As well as commissioning the review, the Government said it would be making clear to all those who had received a letter in the past, as part of a deal Sinn Fein struck with the previous Labour administration, that if evidence now existed, or emerged in the future, which linked them to an offence they could be questioned or prosecuted.
Mr Robinson claimed that move represented a fundamental change to how the scheme had operated before.
"I think that makes it clear that they have a fairly worthless piece of paper," he said.
The DUP leader added: "I think there will be a lot of on-the-runs who will sleep less easy tonight."
Mr Robinson said he now had no need to tender his resignation.
"I do not intend to resign, on the basis that if you get what you want why on earth would you want to resign," he said.
Details of 187 letters sent to so-called on-the-run republicans (OTRs), assuring them that they would not be prosecuted if they returned to Northern Ireland, emerged when the case against a man charged with the 1982 IRA Hyde Park bombing collapsed.
John Downey, 62, from Donegal, denied murdering four soldiers in the attack in London.
The case against him was ended because Government officials mistakenly sent him one of the assurance letters in 2007 telling him he was no longer a wanted man.
But the collapse shone the light on the wider policy of sending such letters to on-the-runs, with unionist politicians in Northern Ireland reacting with fury, claiming the scheme was operating without their knowledge.
Announcing the review this afternoon, the Prime Minister said he accepted calls for a "full, independent examination" of the process.
"I agree with the First Minister of Northern Ireland that, after the terrible error in the Downey case, it is right to get to the bottom of what happened," Mr Cameron said.
"The case has already been referred to the Police Ombudsman but, as the First Minister has said, we should have a full, independent examination of the whole operation of this scheme."
The judge will be given "full access to government files and officials" and will report by the end of May, Mr Cameron said, with the findings being published.
Sinn Fein has insisted that those republicans who received letters only obtained them because the police were not seeking them in connection with offences - and therefore the documents did not amount to any form of amnesty.
Earlier, Sinn Fein Deputy First Minister Martin McGuinness said a number of other republicans who had applied were denied letters and told they would be arrested if they entered the UK.
"So that information blows out of the water this argument of amnesty or immunity or get-out-of-jail card," he said.
Tonight Sinn Fein Assembly Member Alex Maskey described the review announced by Mr Cameron as "unnecessary".
"It has already been made clear as recently as yesterday by the British Attorney General (Dominic Grieve) that the scheme in operation was lawful and proper," he said.
"Given that reality, I have to say I'm not sure what there is to inquire into.
"What cannot be challenged is the integrity of the scheme or the good faith of those who have been processed through it. These people have gone through a process and it has been established that they are not wanted for questioning or charge. That fact can't be changed.
"This announcement is a political fig leaf for the DUP to try and get them off the hook they jumped onto over the past few days."