Yes, I thought it lookked a bit Celco ish. Since posting, I have found out more information. It turns out that one of the circuit boards is marked EFS-Celco, EFS were a desk manufacturer in the early 80's which merged with Celestial Lighting to become Celco in about 1985. So not exactly a prototype Celco 30 but more like an ancestor I think! I have a few Celco desks, and stumbled across this recently. I haven't bought it yet, so am relying on photos from the current owner. Apparently it came from a house in Esher, Surrey, possibly built into a wooden console with a sound desk. Not sure where it came from originally!