I have a glass insulator set available if your interested.
QUOTE=Chris Suslowicz;478318]I have not seen the the block type before, but that looks to be only for a receiver aerial.
The glass insulator with the metal mounting is RAF, I think, and has a metal pipe on the back, and a knurled nut on the aerial end. They were used on aerial junction boxes (Co-axial cable to wire aerial, etc., for ground stations but probably had other uses.)
The two glass bowls... are for the 'blackout box' on the front wall of a radio box. They fit into two Tufnol or Paxolin squares about 0.25" (5mm) thick, and have butterfly (wing) nuts on the end to attach wire feeders (to variometer inside and aerial base outside).
There is a complete unit on eBay, but I will make no comment regarding the price! :wow:
It does have useful photographs of the assembly.