The 1980 Walker report on RUC Special Branch has been something of a holy grail for documentary researchers of the Troubles. After a long-running campaign, the Committee for the Administration of Justice has published a redacted version (PDF) released by the Police Service of Northern Ireland.
The Rights NI blog has a valuable analysis of the document by Brian Gormally:
All in all, the Walker Report is a blueprint for how to turn a police force into a conflict-fighting weapon where victory against the “subversives” is the overriding priority and traditional functions such as preventing crime and upholding the rule of law are sidelined.
As Gormally notes, there is no mention in the report of Walker's own organisation, MI5.