An IRA man who escaped prison more than 50 years ago was given a royal pardon by Margaret Thatcher's government, official records from 1985 revealed.
Donal Donnelly fled Belfast's Crumlin Road jail - which he dubbed Europe's Alcatraz - on Boxing Day 1960 while serving a sentence for membership of the armed group during its 1950s border campaign.
Former Northern Ireland secretary Lord Hurd, part of a Conservative government scarred by republican violence, agreed to use the Royal Prerogative of Mercy in May 1985.
His decision was made less than two years after the biggest prison break-out in UK history by 38 republicans and ahead of landmark political talks on British co-operation with the Irish Government.
A Northern Ireland Office (NIO) letter from the time said: "The Secretary of State has approved the recommendation ... that the remainder of Mr Donnelly's sentence should be remitted."
Donnelly, who was serving a 10-year sentence when he escaped, wrote a book in which he described using hacksaw blades, torn sheets and electric flex as makeshift tools. The title of the book was Escape From Crumlin Road, Europe's Alcatraz.
Afterwards he lived openly in the Irish Republic.
Official files released by the Public Records Office of Northern Ireland (PRONI) reveal Donnelly petitioned three times for the remainder of his sentence to be remitted.
The use of pardons following the 1998 Good Friday peace agreement was disclosed earlier this year after the dramatic collapse of the trial of a man accused of the Hyde Park bombing.
Records released today shed light on the thinking of senior civil servants considering the controversial practice much earlier, while the conflict was still fierce and when Lady Thatcher's government was adamantly opposed to granting any concessions to republicans.
The month Lord Hurd approved the pardon he was tasked with overseeing talks with the Irish Government on the Northern Ireland issue which led to the Anglo-Irish Agreement.
Less than a year earlier, in October 1984, the IRA targeted a Conservative Party conference in Brighton in a bombing which nearly wiped out the cabinet.
An NIO official suggested: "I cannot help feeling that given the Northern Ireland situation, the time will never be exactly right.
"However the prisons are quiescent at the moment, the Maze escape is 18 months behind us and the trial of the recaptured escapers is some months ahead.
"If we hold off until the late summer we may well end up deferring action yet again rather than remit Donnelly's sentences during, or immediately after, that trial."
An extradition agreement between Britain and the Republic was introduced in 1987 and the first extradition happened some years later.
The senior NIO official said: "Generally there is agreement that the remainder of Donnelly's sentence should be remitted.
"I would therefore propose that we should do so now in the wake of the local government elections while the prisons are generally quiet and before 25 June when the trial of the recaptured Maze escapers will focus attention back into this area."
He was referring to a break out by a group of IRA men, including senior Sinn Fein MLA Gerry Kelly, from the high-security HMP Maze.
One prison officer was killed and another seriously injured. Six other warders suffered gunshot wounds or stabbings.
The trial concerned a claim for compensation by three recaptured escapers for alleged ill-treatment on their return to prison.
The court prosecution of all recaptured men for murder of a prison officer and attempted murder was expected to take place that autumn.
Lady Thatcher had become famous for her unbending handling of the IRA's prison hunger strike of 1981 in which 10 men died including Sinn Fein MP Bobby Sands.
But her signing of the 1985 Anglo-Irish Agreement strengthened ties with Ireland and paved the way for the 1998 peace agreement which ended violence and allowed for the release of conflict prisoners.
Current Northern Ireland Secretary Theresa Villiers has revealed that the royal prerogative was exercised in Northern Ireland on at least 365 occasions between 1979 and 2002.
But the true total may well be higher as the NIO has been unable to find the records for the 10-year period from 1987 to 1997.
An NIO spokeswoman said: "The use of the Royal Prerogative of Mercy has changed significantly since 1985.
"The introduction of the Criminal Cases Review Commission, statutory provisions on sentence remission for assisting offenders, and other routes for cases to be reviewed by the courts, mean that use of the RPM is now far more rare. It has not been used in Northern Ireland since 2002."
Mr Donnelly, 75, said he applied for a pardon because he was a planning and procurement manager with a multinational firm in the Republic and wanted to work for the company in Northern Ireland and Great Britain.
"They knew that I was not involved with the Provisional or the Official IRA; effectively I was no threat to them."
He added that the British Government may have been willing to make concessions or display intransigence about relatively minor things depending on its relationship with its Irish counterparts.