The Irish Government released repatriated prisoners after the last week of the British parliamentary term ended in the summer of 1998 following a request from No 10.
Confidential State documents released this year show that the timing was sensitive due to the death of Andrew Kearney following a paramilitary-style shooting in his Belfast home in July.
The British Government had conveyed its concerns to an Irish official that a prisoner release that week could “put their decision as to organisations up in lights”.
The documents also show that Taoiseach Bertie Ahern called UK Prime Minister Tony Blair about the release of the man convicted of murdering Lord Mountbatten in 1979.
Archive files show that there were calls made between the Taoiseach’s office and No 10 about how prisoners were to be released as part of the terms of the Good Friday Agreement.
On Monday July 27 1998, the assistant secretary of the Taoiseach’s office Walter Kirwan relayed notes taken from a call with No 10 official John Holmes.
During the call, they discussed the release of prisoners and the timing of any such releases.
“It was for us to make our decisions but the British would greatly prefer that there not be releases this week,” Mr Kirwan wrote.
“They were in the last week of their current parliamentary term and would have to make secondary legislation this week on what organisations were judged to be on a valid ceasefire, so that their prisoners would be eligible for early release.
“This was against the background where the Provisional IRA had almost certainly killed somebody last week. If we were to release prisoners this week, it would put their decision as to organisations up in lights, which they would wish to avoid, so far as possible.”
Mr Kirwan said that Irish ministers and officials had considered how Mr Kearney’s killing should affect the timing of releases, and that while some had suggested it could result in a “slowing” of the process, other considerations “might point in the opposite direction”.
He said that he had told Mr Holmes that decision had not yet been made and said he would get back to him.
In a second document dated from the same day, Mr Kirwan conveyed that no releases would take place during the final week of the Westminster term, and that Mr Holmes was “appreciative” of that.
He told the No 10 official that the Irish government was to release three repatriated prisoners, whose names they believed the British government had no difficulties with; and four other prisoners, one of whom could cause difficulty.
The Taoiseach was to phone the British Prime Minister about the release of the prisoner who “might give rise to controversy”: Thomas McMahon, who was sentenced to life in prison for the murder of Lord Mountbatten and three others off the Sligo coast in 1979.
When Mr Kirwan phoned Mr Holmes on Monday afternoon to update him on the Irish government’s plan, he said the official showed “no perturbation” at the mention of the murder of Queen Elizabeth II’s second cousin.
Mr Kirwan noted that “there had been a feeling that the hour of any releases should be carefully chosen with a view to avoiding or minimising publicity”.
He added that he spoke to Mr Ahern who said that ministers felt there should be a delay in releases because “the Republican movement should not be allowed take away the feeling that outrages could happen with impunity”.
“He indicated that the British could be told about Government concern about the Kearney killing and that no releases would take place here during the current parliamentary week in London.”
The document notes that the assistant secretary at the Department of Justice pointed out that Mr Ahern had committed to prisoner releases by July, and if that were to change Sinn Fein would need to be notified by July 28.
The note states that Mr Kirwan had the impression that the releases would take place on Friday July 31.
Mr McMahon was released from prison on August 6.
The material can be viewed in the National Archives in file 2023/154/14