brilliant sleuthing, thankyou Chris.....
I know the Silent Key was an early (1950s) Guru on the WS10 and radar, we had a WS10 set-up on the coast near here.... and then he went commercial and opened a repair and component supply shop...so he had some fascinating kit at his SK sale.
GL/Radar seems, now
, very very likely.....
now to find someone operating or restoring one.
I even have a Broad Arrow marked cavity magnetron.
Thanks again for your insights.
Brent