Secret Life of Bletchley Park - McKay Sinclair [38]
Already, the question of security was paramount. Should the senior ranks of the general military be allowed to know the provenance of this rich seam of intelligence? The problem was that the more people who knew, the more chance that the Germans might learn of it too.
Something of this tension is revealed in an earlier letter written by Alistair Denniston to Commander Saunders of the Royal Navy. It began: ‘Dear Saunders – I am about to speak bluntly’, and continued thus:
I wish to have it made quite clear that all matters cryptographic are to be dealt with by GC and CS.
To take specific instances:
1) Why was it necessary for [your forces] to copy out the portion of the German Air Code salved at Scapa Flow? It turned out to be a portion of the code used by the German Air Force which had been broken by the Air Section of GC and CS. It required expert handling to obtain full value and a certain amount was lost by being handled hastily and stuffed into tight little envelopes.
2) Why are notebooks from prisoners not sent at once to GC and CS for first examination? …
The memo continued, rather saltily:
If your staff have not enough to do on their legitimate work, it might seem that you are overstaffed … It is being asked here, in the event of the Enigma machine being captured, why you would consider it your duty to investigate it before it reached Knox and his trained staff.
Such a situation would become intolerable and I do hope you will exert yourself to stick to your own job which you are doing so well and not butt in on the jobs of others who are obviously better qualified to carry them out. We have the means of a very efficient co-operation and I do not propose to let any personal sentiments spoil it.3
Even though the Park had done very well in principle by breaking the Yellow key, the fact was that none of the intelligence it gathered was used in any form throughout the Norwegian campaign.
And, in these early days when codes were broken ‘by hand’, there was already a certain amount of resistance among high-ranking officers not in the know; they were concerned about this seemingly miraculous stream of information, and whether or not it could be trusted. With the nature of Bletchley not being mentioned to anyone – especially in the early months of the war – it had to be assumed by military commanders that information was being supplied not by codebreakers, but by spies on the ground. And spies, however useful in some sense, were also notoriously unreliable. As the conflict unfolded, there were to be instances when vital tips picked up at Bletchley Park were dismissed by senior officers simply because it was felt that the information had been gleaned from untrustworthy quarters.
‘The German strategy,’ wrote codebreaker Jack Copeland, ‘was to push Britain towards defeat by sinking the convoys of merchant ships that were Britain’s lifeline, bringing food, raw materials, and other supplies across the Atlantic from north America.’4Throughout 1940, those U-boat ‘wolf packs’ succeeded in sinking hundreds of ships. Yet there had been a further turn in Bletchley’s fortunes in February 1940. In the dark waters of the bitterly cold Firth of Clyde, near Glasgow, a German U-boat – U33 – was detected as it was laying mines in the mouth of the estuary. HMS Gleaner, a minesweeper, detected the craft, and released depth charges which brought it to the surface. Its crew, stranded in the open, freezing waters, were forced to surrender. On board the submarine was an Enigma machine. In the pockets of one of the submariners were three of the machine’s code wheels.
Bletchley thus discovered that the naval Enigma was using a choice of eight code wheels. The Hut 8 codebreakers, led by Alan Turing, realised that they faced several colossal problems. Not only were the naval Enigma operators more disciplined than their counterparts in the army, tending to make fewer mistakes such as repeated