ABSTRACT
In the weeks following the fall of France, SIS came under particular pressure from the Directors of Naval, Military and Air Intelligence to provide at least 72 hours’ warning of any impending German invasion of the United Kingdom. A second urgent requirement was for intelligence that would enable the Royal Navy and the Royal Air Force to mount effective attacks on commerce-raiders, blockaderunners and U-boats operating from ports on the French Atlantic coast. This pressure on SIS was all the greater in that none of the other possible sources of coverage of these intelligence targets could be relied on to supply, or even make a regular contribution to, the required information. The Admiralty’s own direction-finding organisation was new and at first produced little, if anything, of value; and the same was then true of GC&CS’s cryptanalysts and the RAF’s photographic reconnaissance units. Indeed, cooperation between the Admiralty and the Air Ministry over air reconnaissance had reached what Godfrey, the Director of Naval Intelligence, called its ‘nadir’.1
