The APE(X)C, or  All Purpose Electronic (X) Computer  series was designed by Andrew Donald Booth at Birkbeck College, London in the early 1950s. His work on the APE(X)C series was sponsored by the British Rayon Research Association. Although the naming conventions are slightly unclear, it seems the first model belonged to the BRRA. According to Booth, the X stood for X-company.
One of the series was also known as the APE(X)C or All Purpose Electronic X-Ray Computer and was sited at Birkbeck.