Search online for “ BBC Engineering Monograph No51 - Radiophonics in the BBC”
for some more good info and pictures. I have a jealously-guarded original copy.
In the late seventies I actually joined the BBC with the sole intention of working in the Radiophonic Workshop; it didn’t happen. I was promptly pushed into television engineering and the excitement of PAL video. I did visit Maida Vale on a number of occasions and eventually managed to wangle a short informal attachment to engineering there. By that stage ( early-mid 80s I would guess) there was little of the classic gear left.
The other Engineering Monographs are also definitely worth a read, covering a very wide range of topics from when BBC engineering was a force with which to be reckoned
Cheers
Pete