Hi lazydaisy,
As Hercule Poirot stated there was a Rediffusion Factory in Pontypridd. I has an uncle that worked for Rediffusion out of this building in the 1960's. It is on the corner of Common Road and Llanover Road, Pontpridd and is now called Llanover House, this part of Common Road was also known locally as the Corn Stores Hill.
Hope this is of some use to you.
Retpara.