One of these "TV Master"? https://en.wikipedia.org/wiki/Binatone https://en.wikipedia.org/wiki/Binatone - identifiable by the distinctive orange/black casing.

One of these "TV Master"? https://en.wikipedia.org/wiki/Binatone https://en.wikipedia.org/wiki/Binatone - identifiable by the distinctive orange/black casing. I had a Mk.8 in the early 90's picked up from a junk sale, and it had an interesting set of pong-a-likes.