By Dominic Casciani
BBC News Online at the National Archives
Former Prime Minister Sir Edward Heath demanded to know why IRA leaders were not being arrested as they appeared at funerals in the 1970s.
IRA funerals: Republican leaders would attend
But he was told it would be almost impossible to arrest republican leaders without causing bloodshed.
He made the demand after high profile appearances at republican funerals.
It was suspected the leaders were hiding in the Irish Republic and were being smuggled back and forth to boost morale.
Sir Edward began asking what was going on after three senior republicans had been seen wandering around freely at funerals for IRA members killed by the security forces.
Sean MacStiofan, a wanted man on both sides of the border, and Daithi O Conaill, were two of the key men behind the Provisional IRA which had become the main republican organisation by 1973. A third, Cathal Goulding, led the smaller Official IRA.
Documents released at the National Archives reveal Northern Ireland officials explained to the prime minister what had happened in each case.
"The prime minister may be assured that there is certainly no deliberate policy of refraining from arresting such persons," said the briefing.
"There is no doubt that many people knew or could easily have guessed that there would be a liberal sprinkling of IRA leaders [at funerals]."
Officials told the prime minister that the security services could theoretically launch "snatch operations" but a "price would be paid".
In the case of one funeral, officials said attempts to lift Cathal Goulding would be extremely difficult.
"IRA sympathisers would not have let Cathal Goulding be arrested without giving a lot of trouble and the political significance of an incident in which lives might well be lost and many persons injured has to be weighed in the balance."
However, the prime minister was not satisfied.
"His own inclination [is] that they should be arrested and tried and he would like to know what the objections are to doing this," came the reply from Downing Street.
Graham Shillington, chief constable of the Royal Ulster Constabulary, was invited to explain.
Sir Edward: Demanded action
"The places where the arrest of such persons would be likely to occasion disproportionate disorder are in the enclaves or elsewhere at a public meeting or procession," he said.
"Unless there existed strong evidential proofs of a serious criminal offence, contemplation of such an arrest would be most unlikely."
In other words, unless republican leaders were caught in the middle of a suspected terrorist act, there was little the police felt they could do.
Furthermore, officials conceded that there was probably very little police officers could do if they apprehended the men at roadblocks or checkpoints.
"They should be naturally frisked and indeed asked questions," the PM was told. "But what if both proved negative? Is the policeman or soldier to send them on their way without further ado?"
General Sir Harry Tuzo, the head of the army in Northern Ireland, agreed it was difficult to make arrests.
Documents recently revealed he had opposed the introduction of internment, fearing it would make it twice as difficult for him to combat the IRA.
He saw merit in a system where IRA leaders would be regularly subjected to interrogation - but he sympathised with the fears of the chief constable that it could lead to more harm than good.
Despite continued demands from Downing Street, the Northern Ireland Office refused to agree to a blanket arrests policy.
"The furthest we can reasonably go in giving guidance to the security forces," officials told Sir Edward, "is to say that an arrest should be made, provided first, it is clear that there is enough evidence to found a good expectation of being able to secure a conviction for a criminal offence, and secondly that the arrest can be effected without occasioning disproportionate disorder.
"To arrest a visiting IRA leader with a view to internment would be political unwise.
"So often we would be wiser not to act and be prepared to defend this exercise of discretion."