The Royal Family were a problem in the first half of the 20th Century because they were Germans. Geoge I and his family came over in 1714 and every one of their descendants married German princes or princesses. Unlike the preceding French lot they hadn't been competing for the German throne, and were in fact still friendly with their relatives over there.
There had been, during the Great War, quite a row because the Royals were reluctant to strip the Kaiser of his various British honours (including being honorary Colonel of several British Regiments). OK, we were at war, but Willy was still Family!
So yes, the Royal Family needed to be watched. Edward VIII had taken himself out of the equation with an ill-considered marriage to an American divorcee. A move his great-great nephew was to repeat with rather more calculation. George VI was felt to be a better bet because of his marriage to the Franco-Scots Elizabeth Bowes-Lyon, who was in complete control of her nice-but-dim husband and could be expected to favour France rather than Germany.
Hess was, of course, barking mad, but it is also thought that he believed that by engineering peace with Britain he could regain Hitlers' favour. As to his 'suicide', I'd be more inclined to put it down to the Mossad than to MI6. The increasing pressure to release this broken old man would have been enough to trigger the more vengeful factions in the Israeli government. Embarrassing revelations could have been put down to the ramblings of a senile old man.
George of Kent was a known philanderer, suspected drug addict and rumoured bisexual. In short, a security risk. He was sidelined into RAF welfare work and is said to have been at the controls when the plane crashed.
Winston Churchill was never told about anything important until after it had happened because the man was an idiot. His entire wartime career was one big publicity stunt.
Those papers will be found to have been destroyed in a fire, accidentally shredded in the 1950s or 'rendered undecipherable due to having been stored improperly'. Only the most vanilla ones will be released -'twas ever thus.
Operatives of the Security and Intelligence Services often ended their lives in psychiatric hospitals. Too often, they were never fully or properly debriefed, leading to PTSD in later life.
