5 year update!
It was built by the Decca Navigator company. After they were taken over by RACAL I was the Chief Avionics Instructor for a while and was shown one on visiting the avionics maintenance unit at Heathrow, as an example of a museum piece. A year later on re-joining the RAF I was using one for real in a VC10. They were replaced by a combination of Carousel and Omega removed from EX BOAC VC10s in the mid life update in 1987/88.