The History of Hut Eight

in the totally illusory hope that they had discovered a feasible method of breaking keys. This comment does, of course, assume that a right reencodement will be available later, as was in fact normally the case. If there had been no reencodements, their policy would have been justified because Shark was a vital key and there was no other way of breaking it; at the end of the Short Signal period we ourselves had been running a long series of feeble cribs for want of any other method of attack. An alternative occupation for bombes was Turtle, the Mediterranean U Boat key which had separated from Shark in June. Turtle was always a dull key and the policy was to run it when a certain reencodement from Shark was available; at the end of 1943 Turtle was handed to Op-20-G so that they might have a key of their own, but here again they launched out on a crib policy which proved unjustifiably expensive.

The position was rather an embarrassing one. Milner Barry's axiom that "Policy directing the use of bombes is decided here on an inter-service level, and the bombes are in practice regarded as common property for the general war effort. Other considerations such as what service actually built the bombes and for what original purposes are irrelevant" was clearly not being adhered to, but Op-20-G had many more bombes than ourselves and killing geese which lay golden eggs is a poor policy. Fortunately the solution of the problem was made much easier by 3 developments:

1. The appearance on Shark of the new Biscay Weather crib.
2. The increasing skill and wisdom of the Op-20-G cribsters.
3. The steady increase in the number of Naval keys and the general introduction of the 4 wheel machine.

Biscay Weather we have met as a very seedy crib which rarely broke a day, but right at the end of October it produced a lengthy form and continued to use it with minor alterations until after the opening of the Second Front in 1944. It was a terrific crib, certainly the longest consistent crib we ever possessed and the number of freak forms it produced was small. In January 1944 the Security Services spotted it and sent a signal to the originator in Shark: "Biscay Weather appears daily at an almost identical time, much of the text is identical, the length identical, the beginning identical, and it is always repeated on the 'Ireland' frequencies....." This made curiously little difference except that it was now usually sent out independently on the 2 services and the security officers would have been as surprised and pained as the magician's apprentice who chopped the broom in two if they had appreciated that they had given birth to 2 cribs in place of 1 - though one of the two was pretty bad. The effect of this crib was normally to break Shark currently and so in most cases to remove the problem of Op-20-G running bad cribs because there was nothing else to run. During these months also their general wisdom and ability to assess their own cribs rapidly increased while increasing numbers of Naval keys made it possible to give them more


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