McVitie Weston valve collection, STC valve, type 4H/180E
STC valve, type 4H/180E, internal electrode marked LUS.2., (RMW/Y520 - McVitie Weston number), by Standard Telephones and Cables Limited.
STC valve, type 4H/180E, internal electrode marked LUS.2., (RMW/Y520 - McVitie Weston number), by Standard Telephones and Cables Limited.