I have tried twice to get inside Belfast XR371 which I flew to Kemble from Brize at the end of its life with 53 Sqn
Well that is so petty of them. It should be a privelage for them to have one its ex pilots visit the aircraft, with log books to prove. They should even take advantage and take photos "ex pilot visits..." for their newsletters/magazines/website. This to me is the most compelling reason to be allowed to visit a certain aircraft, the pilot himself.
"It's an insurance problem" is the usual excuse.
What a load of crud ! Their loss JW. I would write to the RAF museum's director if I were you. Good luck.