Kim Philby by Tim Milne Read Free Book Online

a small proportion of German intelligence telegrams. At the end of the year there came a radical change. I was staying down in Dorset for Christmas when Kim rang me in the guarded language used on the open telephone: ‘You remember the possibility we discussed that you might have a tremendous increase of work? Well, you have.’ I returned to St Albans to find the first decoded messages from the machine cypher links on my desk. Within a few weeks I was having to study anything up to 120 a day: nearly all were Abwehr , a few SD. (I should mention that the term ‘ISOS’ strictly referred only tothe hand cypher material, while the machine cypher material was given the code-name ISK; † but unofficially ISOS continued to be used as a generic term for the lot, and I shall so use it here.)
Although ISOS was distributed also to MI5, to specialised sections in the three forces ministries and to a few other people, it had been agreed by the chief that the prime responsibility for action on it lay with Section V. This responsibility was in turn delegated to the appropriate geographical subsection. In practice most of the opportunities for doing anything with the information, as opposed to merely studying it, lay with Vd. This is because Spain and Portugal were neutral European countries in which both the Germans and SIS maintained stations, and which gave the Germans their best outlet to Allied territory. In addition the harbour and Strait of Gibraltar were themselves important intelligence and sabotage targets. Since Spain and to a lesser extent Portugal were friendly to Germany, conditions were highly favourable for the Abwehr . But the situation also gave us opportunities for counter-action. The other neutral European countries were on a different footing: Sweden and Switzerland were largely cut off from the west, and Turkey was somewhat remote.
While ISOS was potentially of enormous value to us, the handling of it was hemmed about with difficulties. There was nothing like a 100 per cent ‘take’ of cyphered messages. Abwehr radio transmissions might be missed by the British interceptors, or received in a garbled state owing to bad atmospheric conditions.Of those intercepted, the cyphers might be uncrackable for short or long periods. In addition, a great deal of vital information would be sent through the diplomatic bags between the German consulates and the embassies at Madrid and Lisbon, or between the embassies and Berlin; the bags were of course inaccessible to us. Frequent visits by Berlin officers to the peninsula, or by local Abwehr officers to Berlin, and the use of the telephone, all helped to reduce the Abwehr ’s dependence on cypher telegrams. The messages themselves were often couched in deliberately obscure language, and both officers and agents were normally referred to by cover-names (not to be confused with aliases, i.e. the false names they might be using in public).
More important, our first consideration had to be the security of the source. It was, of course, absolutely vital not to let the Germans even suspect we were reading their cyphers. More than ever this became necessary when the machine cyphers were broken, since these, we were given to understand, operated on the same principle as those used by the German armed forces for their high-grade cypher messages; much has now been published about the Ultra source and its incomparable value to the British and American governments and armed forces. It was impressed upon us that, whatever else we might do or fail to do, the one crime we must never commit was to endanger the ISOS source. I should make it clear that although the risk was much more serious in the case of machine material than with the lower grades of cypher, we treated all kinds with equal care. We did not want to give the Germans the slightest reason to begin examining their cypher security.
As the ISOS officer in Vd it was for me to study all the intercepts affecting our area; piece together