The History of Hut Eight

Naval jobs which they always preferred running to Army or Air keys for Hut 6.

In November Commander Engstrom was over here and after discussion with ourselves and Hut 6 sent the following directions to Op-20-G:

1. (a) All current Amir jobs, meaning for day more recent than any day broken, shall be and remain fully bombes up in sense of not being stinted for other jobs.

(b) We shall send here with Rima numbers any crib we consider worth running and they will assign priority to it in relation to available Amirs.

(c) If we find a Rima when no current Amir is available then we may put it on immediately. But if they consider this Rima not good enough to be worth running instead of an available back Amir then the latter shall be fully bombed up.

2. We shall run all Turtle and will be in full control of Turtle program. They will send any cribs they find with T serial numbers to be run at our discretion.

3. It is agreed on principle that Air keys are considered on same basis as Naval keys other than Shark. Decision between them to be based on current intelligence and operational value but if value about equal Naval key to be given preference. Our representative to be present at weekly meeting here which decides priorities.

The degree of control which this signal implies was gradually relaxed in the course of 1944 as it became obvious that Op-20-G were as well qualified as ourselves to decide which Shark cribs were worth running and by half way through 1944, they had taken over complete control of Shark and undoubtedly knew far more about the key than we did. Our function was to send reencodements from Narwhal or Plaice as they occurred and we played no part in the straight cribbing. The number of days they broke in straight cribs with comparatively small expenditure of bombe time in the very cribless days which followed the death of Biscay Weather represent an extremely fine cribbing achievement.

The acceptance by Op-20-G of the principle of pooled bombe resources was a fairly slow one. An analysis at the end of 1943 of the bombe time used per day's traffic read on various Naval keys showed that on Porpoise the average number of hours was 9, Grampus 11, Dolphin 74, Sunfish 186(?), Seahorse 280, Shark 500, Turtle 1500..... On this the Weekly Report comments:

"We are asking the Americans to give Bovril (Hut 6) jobs preference over weak Turtle menus as these give such poor return for money".

By the time the Second Front opened very close and efficient cooperation existed. Priorities of keys were decided at weekly meetings at which the U.S.N. representative was present and Op-20-G stuck most loyally to the priorities as laid down, running a vast number of Hut 6 jobs and enabling them to break keys which


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