I was sent a photograph (from a book) of a RSS / Y Service site with a
number of disc recorders.
I immediately wonder if they were similar to the ones use by the BBC and
this post below seems to have the same idea.
It is presumed they were used for recording intercepted wireless traffic.
One picture is of a GPO twin turntable disc recorder, another about four
of them.
Ah, yes, looking at the pictures again it might just be a stripped down
version the earlier form of BBC recorder known as the MMS Marguerite
Sound Studios. I att a few pics from the book. The full kit for the
Portable Type C was quite large, but for a fixed logging set up could
have been much more basic.