I doubt whether the fact that it might have brought us into trouble with the Official Secrets Act weighed with us to anything approaching the same extent. It was much more a matter of not ‘breaking ranks’ or ‘letting the side down’. Moreover, we knew that a history of the wartime effort was being written at Bletchley with the hope that this should constitute an impartial record that might be published at some future date: until then none of us should speak.There were in fact occasional breaches, but these were few, and not at the privileged level to which the preceding paragraph refers — apart, of course, from [Kim] Philby and his associates.
The one instance that I myself encountered arose when the author David Irving was writing his book on the German V2 effort and our attempts to frustrate it, The Mare’s Nest. By talking to a former NCO who had been at Bletchley [a Sergeant Harcourt], Irving discovered that the reason why we knew the works numbers of the spent V2s that were being returned to Peenemünde from Poland was that we had broken the line of Enigma traffic in which these numbers were reported.
When GGHQ [Government Communications HQ, successor to GC&CS: the equivalent of the NSA] learned of the leak, two of its officers called on me and told me that it would be difficult for them to proceed against Irving if he insisted on publishing the text. They had come to me because they believed that he respected me, and they thought that there might be a chance that if I were to talk to him he might accept my persuasion not to publish. And so his book appeared without the vital disclosure. Years afterwards GCHQ told me that they could not have risked the publicity caused by a prosecution that would have blown the very secret of Ultra that they were still trying to keep, and that this was why they had sought my help.
Unfortunately I did not see much of Irving for many years following that episode because shortly afterwards he adopted the theory of [Rolf] Hochhuth, that Churchill had organized the murder of the Polish leader, General Sikorski. However, in about 1980 we met accidentally when he saw me trying to find a taxi in South Audley Street to take me to Heathrow. He was driving a Rolls Royce and promptly offered to take me the whole way. The drive was memorable for two things.
The first was Irving’s driving technique, which reminded me of Lord Wavell’s advice on handling an army:
The relation between a general and his troops is very likc that between a rider and his horse. The horse must be controlled and disciplined: he should be ‘cared for in the stable as though he were worth £500, and ridden in the field as though he were not worth half-a-crown.’
Irving evidently regarded his Rolls in the same light; ‘Everyone gives way to a Rolls,’ he commented as we charged headlong from Mount Street transversely into the dense traffic in Park Lane.
On the way I asked him, ‘What stopped you publishing the fact that we had broken Enigma when I asked you?’ His terse reply was ‘Patriotism!’
I tell the story because Irving has at times provoked many of us; but when it is remembered what a ‘scoop’ he sacrificed, surely one of the biggest ever, he has a lasting right to our respect alongside Governor Dewey, who in 1944 and in similar circumstances sacrificed his chance of becoming President of the United States.
I encountered one other instance where the Ultra secret was ‘blown’ if anyone was alert enough to recognize it. It was in Air Vice-Marshal Peter Wykeham’s book Fighter Command, published in 1960. In describing the KNICKEBEIN episode he wrote, ‘By a stroke of luck, Intelligence … [etc]