Op Mikado never materialized and Op Plum Duff´s infiltration by Sea King helo was in the public domain (first, because ZA290 wreck was discovered in Chilean territory and because, later, Hutchings and Ewen ST wrote extensively about that).
Op Kettledrum involved HMS Onyx and SBS troops, but Onyx never went near Puerto Deseado Airbase, the designated target.
Op Shutter remains a mistery.
How the troopers were infiltrated near the airbases? According to James Adams´"Secret Armies", the infiltration was made by submarine. In that respect, the Dagger in HMS Conqueror Jolly Roger could be a "leak" (the "official" explanation - if a Jolly Roger has an official explanation - is because Conx disembarked some SBS near South Georgia)
An helo was involved? A radar echo was detected near Comodoro Rivadavia on the night of May 22nd. A Pucara (first) and a Mirage III (later) was launched to investigate, and informed three helos were in close formation. The Mirage driver locked a Matra 530 IR on a helo but hesitated to launch. The helos, flying with no lights vanished shortly after. There were reports of troops informing the helos were here or there, disembarking troops. Hours later, a sentry in Comodoro Rivadavia base informed about intruders, and a firefight erupted.
Because Op Shutter files are closed, we could only argue about it...
Regards!