There was only one new key during these months - Rorqual which appeared on February 1st and derived its name from the solution of a clue in the Times Cross-word Puzzle. Rorqual was the least Naval of all our keys, containing as it did information about the damage done by Allied air raids on the Ruhr; the information was of interest to Hut 3 and Rorqual had to be broken. Traffic had started in January but was at that time on Plaice keys. Cribs were sensationally good as the originator and destination of all messages were known from the very reliable call-signs. During January, however, we were quite unaware of this possible method of breaking Plaice. All traffic went to Hut 3 from whom we did not receive typed copies of decodes, as we did from Naval Section, so that we ourselves never saw and appreciated the possibilities of the traffic. Also, while the Z Watch would have realized at once that the traffic contained cribs and would have drawn our attention to it, no such arrangement existed with Hut 3 and the cribs remained unexplored. This is not recorded as a reproach to Hut 3 from whom we always received any assistance for which we asked but simply to draw attention to a curious loophole in the crib finding organization. We had always been uncomfortably aware that something might escape us in this way and had taken the risk on the grounds that only a small number of messages were involved. After this episode we came round still more to the view that the only way to be sure that no cribs were being missed was to have all traffic reencoded for the benefit of the Crib Room.
Rorqual was broken as an independent key throughout February and most of March. Towards the end of March cribs began to deteriorate steadily and the Ruhr itself was clearly in imminent danger of being overrun by the Allies. By early April there was no further doubt that Rorqual was moribund and work on it was abandoned.
If January, February, and March were comparatively peaceful, April was just the opposite. In the first place we ran out of Sucker keys and Sucker had to be broken to get reencodements into Dolphin; this was possible but difficult and led to delays on both keys. The situation was made worse by the Germans fearing that the Sucker keys had fallen into Allied hands as a result of which individual fortress keys were used extensively in the middle of the month; on one occasion we ran a crib which was normally on Sucker only to find that we had broken not Sucker but the private key for Dunkirk, a totally useless accomplishment from our point of view as this gave no reencodements into Dolphin. Later in the month, on the 20th, May keys were used on the equivalent April days as a further measure against possible compromise; unfortunately the war did not last long enough for us to reap the benefits of knowing the keys for the end of May in advance. To make matters worse the Hoofden weather ceased to appear in Sucker towards the end of April and prospects of breaking Dolphin seemed gloomy in the extreme as straight cribs were practically non-existent. The situation was saved by the capture of Hackle keys: Hackle was an insignificant key in the Netherlands area which we had never attempted to break but at the end of April it started to reencode