78 Sqn Sea Kings have done both rescues and pick-ups of compassionate cases from South Georgia, starting from MPA, which is about 900nm each way, though in fairness a large part of that was spent on the back of a Grey Funnel.
Seem to remember Captain Cardiac (you know who you are!) doing some long range epic from the FI several years ago to pick up a woman with heart problems from a cruise ship. Involved refuelling from one her majesty's grey funnel war canoes and anecdotal evidence suggested that the co-pilot touched the controls for about 15 mins in some 8 odd hours! I don't know the range, perhaps someone with closer knowledge might have an accurate figure....
From what I know, that would be 15 mins +0/-15! I heard an amusing tale from a D Flt RadOp who arrived there under a bit of a cloud while the by-now Major Cardiac was in command...the RadOp said that MC blanked him for the entire first shift they did together, and even when they got a job the RadOp wasn't allowed to speak - he says that, when they arrived on scene, MC did all the briefs including the recce and method brief, and the first thing the RadOp managed to say on the sortie was "Winching Out"!