between the B.P. group and the Harpenden group and the CRR staff at
Beaumanor. "Traffic analysis" of the Wehrkreise network was the
principle bone of contention. As reports and summaries of their
findings began to be published by each, the cryptographers at B.P.
principally Mr Gordon Welchman, became interested in possible
cryptographic aids to be found from log reading. Discoveries of
re-encipherments were brought to his attention by both Lithgow and
Blair-Cunynghame. The question of moving the Harpenden group (of
the War Office) to B.P. (of the Foreaign Office) was raised but in
fact the move was to Beaumanor (by then associated with the War
Office) where the combined efforts of the Beaumanor CRR and the
Harpenden log readers could be applied to the Wehrkreise problem.
the move to Beaumanor was sometime after Beaumanor became attached
to the War Office because of the employment of A.T.S. operators
and Mr Ellingworth, its head, became a Lt. Col.
After the move to Beaumanor, Thompson (now Lt.Col.) was put
in charge with Blair-Cunynghame as his operational chief. There
the notion of a Fusion Room develped. However, not all decoded
traffic at B.P. was distributed to the "fusion" party. Call-sign
analysis, in the meantime, had been developed by the group under
Blair-Cunynghame, and the possibility of limited prediction of call-
signs was becoming very useful for interception. Late in 1941 the
Bird-book was captured in Africa and this knowledge was fully exploited
by the Beaumanor group. A weekly W/T.I. report, called "The Beaumanor