Where do you start Graham! there's a fair old mix in the top photo of gas pipes, electrical conduit (both original and as added for the ETH conversion and brake pipes for the dual brake conversion)! The bottom photo shows the two main air pipes attached to the bottom longitudinal, with the ETH conduit above and to the rear of it the (lagged) main steam heating pipe - and interesting for you, the ETH main fuse box - sitting up behind the solebar.
Bob.