Michael Havers, then attorney general, told SDLP leader John Hume during a lunch in April 1987 that there would be “shocks felt throughout the force” over the so-called Stalker affair.
During the meal, arranged by an Irish diplomat who reported back to the Taoiseach’s office about it, Mr Havers was “quite forthcoming” on what was one of the most controversial episodes of the Troubles.
“He said he now has grounds for believing that he will be undertaking prosecutions within the RUC ‘which will go high, as high as chief superintendent’,” he told Mr Hume and the diplomat.
“He said he does not think that then chief constable John Hermon himself will be brought down by it, but that there will be shocks felt throughout the force.”
Former police chief John Stalker was asked to investigate RUC shootings of six people but was removed from the inquiry shortly before it was due to report in 1986.
He was taken off the case at the moment he believed he was about to obtain an MI5 tape of one of the shootings.
Suspended over allegations of associating with criminals, he was later cleared of any wrongdoing and reinstated in his job as deputy chief constable of Greater Manchester Police but his report was never published.
Declassified files show Mr Havers told Mr Hume he intended to “bring forthrightness” to the case.
“Havers said that if they think they can operate that way, then he has every intention of rooting them out,” reported the diplomat.
In an addendum, he noted that “there may be some element in this of Havers trying to please Hume and myself, but he did bang on with what seemed to be a good measure of real conviction too”.
Mr Hume told Mr Havers a public indication of imminent prosecutions in the Stalker affair could be “extremely valuable” to his party’s prospects in the Westminster elections later than year.
The SDLP leader said it would be “just the thing to knock off Gerry Adams and, just possibly, Enoch Powell” in the West Belfast and South Down constituencies.
“Havers responded strongly to this and mused a bit out loud about how much he might possibly be able to engineer it,” according to the file marked confidential.
“He was, he said, very taken by the idea of bumping off both Adams and Powell in one go.”
State files released last year revealed Mr Stalker told another diplomat in November 1986 that he was not concerned so much about a cover-up but “murder, six murders”.
At the time, he had completed reports into five of the six deaths as well as 90% of his report into the RUC and “very much feared now that what he had done will be rewritten by other hands”.