He was one of four founder members of the'Testery' in July 1942 when it was set up to work on the breaking of Tunny the German top-level cipher system.
He was one of four founder members of the Testery Autumn 1941, first he worked on German Military Police double Playfair ciphers. From July 1942 the Testery was switched to the breaking of Tunny the German top-level cipher system.