The Secret History of MI6 - Keith Jeffery [264]
Following Wild Bill’s visit, Menzies told Stephenson that Donovan had been convinced of the necessity for the ‘closest co-operation’ between the FBI and SIS, and was also prepared to advocate that Army and Naval Intelligence should similarly co-operate with the British. For his part, Stephenson was delighted to report that Donovan had ‘strongly urged our case regarding destroyers and other matters’ to the United States government, and it seems clear that Donovan’s strongly expressed views (as well as Lothian’s and Stephenson’s lobbying) played a significant part in paving the way for the September 1940 agreement by which the USA agreed to provide the United Kingdom and Canada with fifty badly needed destroyers in exchange for rights to bases in British possessions. Stephenson reckoned that Menzies indeed had played a crucial role in cultivating Donovan. ‘Give yourself fifty pats on [the] back sometime,’ he cabled on 4 September. ‘Without Colonel, it could not possibly have happened at this time.’7
Another developing liaison which personally involved Menzies concerned signals intelligence. In October 1940 Stephenson told Menzies that the American Military and Naval Intelligence departments now favoured a ‘full exchange’ of all known information on enemy and other codes and cyphers. Having discussed the matter with the armed service Directors of Intelligence in London, Menzies agreed that ‘a pretty free interchange of cryptographic information’ would benefit both the United Kingdom and the United States, and proposed that an American expert be invited to Britain to discuss the matter. If the expert ‘made a favourable impression’, work on Italian and German cyphers could be considered. There was, however, a limit to what might be covered, as Menzies explained to the Director of Military Intelligence. He had discussed the matter with Sir Alexander Cadogan, who agreed that ‘we cannot possibly divulge our innermost secrets at this stage’. Menzies’s main interest, in fact, was in sharing expertise in attacking Japanese codes, but he worried that restricting any discussion to Japan would ‘almost certainly give a measure of offence, as clearly indicating that we have something to hide’. That was perhaps the least of the government’s worries, as one official, bearing in mind that GC&CS had been attacking American diplomatic signals traffic for years, minuted: ‘What will they think if they find we have been reading their own stuff?’ On Menzies’s advice, however, Churchill agreed not to limit the discussions to Japan.8
The Americans, who brought with them a reconstruction of the Japanese diplomatic cypher machine code-named ‘Purple’, visited Bletchley Park over several weeks early in 1941. The discussions went very well, and, at the behest of the Chiefs of Staff, Menzies secured Churchill’s permission to reveal ‘the progress which we have made in probing German Armed Forces cryptography’, though for the moment the discussions were to be ‘confined to the mechanized devices which we utilise and not to showing the results’. Although this decision ‘was thought inadvisable in some quarters’, Menzies firmly defended it as ‘a wise one’, as it led to GC&CS acquiring important new Japanese material.9 This American cryptographic mission to Britain marked a very significant step in the developing Anglo-American intelligence relationship, and the episode illustrates the extraordinary extent to which the British were prepared to reveal (albeit with some understandable reservations) among the most sensitive of all their intelligence