Comet wingtips
Whilst working, in the 1950's on the BOAC Comet 2 at Marshalls being converted to RAF flying classrooms , I opened a small panel door just under the wing tip .
It was a mini box section with no access to lights etc .
I was then informed that it was a place to transport medical isotopes,to and from various places,well away from passengers . Any ideas as I think this area was also on Comet 4's when I was on the production line at Hatfield