Hut 8 closed down rapidly after the surrender, there being little to do except clear up. After May 21st only 2 of the staff of about 130 were left.
Hut 8's accomplishment consisted in decoding during the course of the war about 1,120,000 messages; the total number of intercepts received was about 1,550,000. It is remarkable that since regular breaking began in the autumn of 1941 the situation has always been under control and no important key has ever ceased to be broken with the exception of Shark between February and December 1942. This continuity of breaking was undoubtedly an essential factor in our success and it does appear to be true to say that if a key has been broken regularly for a long time in the past, it is likely to continue to be broken in the future, provided that no major change in the method of encypherment takes place. This was the great failing of the German cypher authorities and the lesson is clear for anyone concerned with cypher security to read; the Germans introduced their cypher innovations seriatim and gave us time to recover from each blow before delivering the next. The introduction at one fell swoop of all the changes which took place, for example, in 1944 would doubtless have put us out of business but as a result of the methods the Germans adopted we were able to preserve continuity and breaking continued. The developments which were scheduled to take place during the months following the surrender appear alarming, but I believe that we should have survived these also for the same reason.
In finishing this account of Hut 8's activities I think that it should be said that while we broke German Naval Cyphers because it was our job to do so and because we believed it to be worth while, we also broke them because the problem was an interesting and amusing one. The work of Hut 8 combined to a remarkable extent a sense of urgency and importance with the pleasure of playing an intellectual game.