Chugalug 2, I strongly suspect that the documents will refer to the Duke of Windsor. A known racist, he and Wallis (about whom there is also much speculation) were bundled off to Bermuda during WW2 where there was less chance of them causing problems for Britain during the war.
Despite the RAF dress regulations mandating its use, to this day the royals refuse to use the Windsor knot when in RAF uniform and are, ipso facto, incorrectly dressed. Not that any SWO is likely to pick them up though!
Other possibilities are the documents pertaining to the interrogation of Rudolf Hess and 'Box24' of the Duke of Windsor's archives which may reveal pro-Nazi sympathies, although some consider that his contact with Hitler was merely to appease Nazi Germany in an attempt to prevent WW2 breaking out.
No doubt if Comrade Corbychev had his way and the British Socialist Republic was formed, the papers would be released rather sooner?