Gravelbelly,
Thanks for the info. One of the ways i've handled this in the past was to use the a/c electrical schematic as a way to identify which boxes were connected to what. It's
easy for older a/c like the Lightning or Vulcan, where all the info is in the public domain now, but more difficult with more modern kit, which may still be covered by the 30 year rule. Hendon were quite helpfull with some AP copies with regard to the early Harrier FE541 ins, so will probably drop them a line. Selex Galileo may be abe able to help, but have been put off in the past by thoughts of the man at the other end thinking stuff like "not another bl**dy anorak enthusiast" :-). Will give them a call anyway and ask to speak to their library, or try to find out who to speak to...
Regards,
Chris