The letter was dated 21 October 1941 and marked “Prime Minister only.” It came from Hut 6 and Hut 8 at Bletchley Park, the huts working on German Army and Air Force Enigma and on Naval Enigma. Four cryptanalysts signed it: Alan Turing, Gordon Welchman, Hugh Alexander and Stuart Milner-Barry.
Winston Churchill had visited Bletchley Park in September. The four opened with that: “Some weeks ago you paid us the honour of a visit, and we believe that you regard our work as important.” They had plenty of bombes, the machines that helped break Enigma. What they lacked was people. “We think, however, that you ought to know that this work is being held up, and in some cases is not being done at all, principally because we cannot get sufficient staff to deal with it.”
Then came the list. In Hut 8, the Hollerith section had stopped working night shifts for lack of staff. “The effect of this is that the finding of the naval keys is being delayed at least twelve hours every day.” To start the night shifts again it needed about twenty more clerks at once. In Hut 6, Middle East traffic that couldn’t be picked up in Britain was arriving, but there weren’t enough trained typists to decode it all. “This has been the state of affairs since May. Yet all that we need to put matters right is about twenty trained typists.” Wrens promised in July to test the bombes’ results had not appeared. That one, they wrote, “has not actually delayed us in delivering the goods,” but it pulled codebreakers off other work.
Writing straight to the Prime Minister broke the rules, and they knew it. “For months we have done everything that we possibly can through the normal channels,” they wrote, “and that we despair of any early improvement without your intervention.” They had written “entirely on our own initiative,” and they asked not to be read as criticizing Commander Travis, who ran the Enigma teams.
Churchill’s answer was dated the next day. It was a handwritten note to General Ismay, his chief military assistant, with a red “Action This Day” label: “Make sure they have all they want on extreme priority and report to me that this has been done.”
On 18 November, Ismay reported back. Brigadier Menzies, the head of MI6, said the labour supply for Bletchley was being met very rapidly. It was “not entirely completed,” but he was satisfied “that every possible measure is being taken.”
Inside Bletchley Park, according to The National Archives, the letter caused tensions when it came to light. The four signatories got a nickname: the “wicked uncles.”