Last week, British newspaper journalists were stopping people in a street in Cambridge to ask about the elderly academic living at number 49 who was not answering his door.
The events are linked. The academic is Theodore Hall, 70, a distinguished scientist who is very ill and has instructed a solicitor to say that he does not wish to be interviewed. And what brought the journalists to his door was the appearance of his name in that 1944 message in a context that proved he had been a Soviet spy.
The message begins as follows: "BEK visited Theodore Hall, 19 years old, the son of a furrier. He is a graduate of Harvard University. As a talented physicist he was taken on for government work... According to BEK's account Hall has an exceptionally keen mind and a broad outlook, and is politically developed. At the present time, H is in charge of a group at CAMP-2. H handed over to BEK a report about the camp and named the key personnel employed in ENORMOUS."
The words in capitals are codenames. BEK is a Soviet agent called Sergei Kurnakov, then active in New York. CAMP-2 is the top-secret Los Alamos laboratory, at that time busy designing the first atomic bomb. ENORMOUS is the Manhattan Project, the $2bn network of reactors, factories and laboratories involved in the A-bomb effort.
The message could hardly be more embarrassing for Mr Hall.Why it has only come to light now, and the long journey it travelled before reaching the shelves of the Public Record Office in London, is one of the great stories of modern counter-espionage.
Along with 2,900 other wartime and post-war Soviet intelligence cables, that message was intercepted by the US Army Security Agency, but the code used could not be deciphered.
Since no one in the United States had any idea of the extent or power of the Soviet espionage system, and since the two countries were allies, the huge pile of papers, all in coded Russian, were put to one side.
By 1947, however, the Cold War was beginning and two brilliant young men, an FBI agent called Robert Lamphere and a codebreaker, Meredith Gardiner, had begun to tackle it. They had some leads, including an old, partly- burned Soviet intelligence codebook, recovered in wartime Finland, and some cables in plain text stolen from the consulate in 1944.
The code involved "one-time pads", a constantly-changing system thought to be unbreakable, but Gardiner and his staff - most of them women - were able to turn up a few shreds. First a few short clusters of words, then the occasional sentence. When a name came up, Lamphere seized upon it.
Gradually, working many hours a day over several months, they began to produce readable material, and to fit together a picture of Soviet wartime intelligence operations in the US. The consequences of what became known as the Venona project were earthshattering for America, and even more so for Britain.
One of the first to be exposed as a spy was Klaus Fuchs, a German-born scientist who was a naturalised British subject and worked in a number of senior positions at Los Alamos. Under the codename REST, he sent long reports to Moscow through the New York consulate.
Fuchs was identified by chance, because one message referred to him visiting his sister, who was a student at an American university - only Fuchs fitted, and he was eventually forced into a confession and jailed.
In the words of Hans Bethe, his boss, Fuchs "told the Russians exactly how to assemble the bomb; how to use implosion; how the explosive and nuclear material was arranged; how to calculate the yield of the bomb and the neutron diffusion, and he certainly told them about the critical mass". It ranks as one of the most remarkable coups in the history of espionage.
The Venona project did not stop there. It lay behind some of the greatest spy scandals of the post-war years, notably Burgess and Maclean, Philby, the Rosenbergs and the Alger Hiss affair. A huge and pervasive Soviet espionage network in the US and Britain was brought to light. In the words of Sheila Kerr of Salford University, who is to publish a book on Maclean next year, "You can't overestimate the importance of Venona as a counter- espionage operation. If they hadn't had it, those Soviet networks would have gone on working for years and years."
As with Ultra, the vital German wartime code which Britain cracked, the role of Venona was kept secret for decades, until the 1980s, and the contribution of Lamphere and Gardiner remained unknown.
Earlier this year the US began to declassify and release some of the papers - leading to the first public identification of Theodore Hall. And Britain, which through the GCHQ listening and codebreaking in Cheltenham had become involved in Venona, has now followed suit with its own set of papers.
The documents in London come in 50-odd files of A4 photocopies, a great splurge of messages, some trivial and some, like the Hall message, smoking guns. They testify to the awesome reach of Stalin's intelligence machine, but they also have moments of bathos, showing us some of the comic and the tedious side of spying.
Evidence of the breadth of the operation is on every page, with its references to spies and agents from Australia to Mexico, from Bulgaria to Canada. In Stockholm alone the intelligence chief in one message lists his agents by codename: "Admiral, Vajda, Barbo, Akma, August, Floro, Mostovik, Berus, Ispanets, Sand, Samuel, Dzhin, Garri, Bard..." and so on for a total of 23 names.
There are also instructions for agents from Moscow on how to handle informants, when to push for more information and when to ease off, which approaches should be followed up and which ignored. Communist Party members who might have information to contribute are monitored. There is an eager exchange between Sydney and Moscow about one who has gone missing, a physicist called Eric Burhop - in fact Burhop was in the US, working for the Manhattan project.
One message supplies the password for a contact that must be made. The agent must ask: "Do you know engineer Vladimir?" He will know he has the right man if the answer is: "Yes, I know him. He is a relative of mine." Another records with regret the loss of an agent, who "has finally fallen under the influence of his wife, being a weak-willed man".
The housekeeping is done through the cables. We know, for example, that in July 1944 the Canberra embassy spent pounds 132 on intelligence work, pounds 111 in August and pounds 156 in September. Salaries, bonuses and other expenses are also accounted for.
The messages also give us a glimpse of the mixed quality of information generated. For example, at the top end of the scale Donald Maclean (codenamed HOMER), the British diplomat who ranks with Fuchs as Stalin's most effective spy, was able to feed Moscow verbatim accounts of exchanges between Winston Churchill (BOAR) and Franklin Roosevelt (CAPTAIN).
Earlier, however, the London embassy had served up some rather inferior fare. It reported a naval informant as predicting where the German invasion of Britain would occur: "The main strike will be from Norway, where the coast is suited to concentration in secret." First to fall, the informant insisted, would be the Shetlands, Iceland and Ireland. The codenames themselvesare often changed, affording almost infinite possibilities for confusion. The Comintern is THE BIG HOUSE, which seems fitting, a member of the Young Communist League is a GYMNAST, Germans are SAUSAGE DEALERS and Britain is THE COLONY or THE ISLAND.
The humour, however, will be lost on Theodore Hall. Exactly when the telling message about him was decoded is not clear, although the markings suggest it may have been as late as 1961.
He moved to Britain in the following year to pursue a career of great distinction in biological microanalysis - the work for which he has made it known he would like to be remembered.
As a junior scientist at Los Alamos, it is impossible that he could have passed on even a fraction of what Fuchs was able to supply to Moscow, so his role was minor at best.
Why he was not prosecuted and whether he moved to Britain because he had been unmasked are questions neither he nor the US authorities have answered. They are among hundreds of questions thrown up by the Venona papers which were addressed at a conference of historians hosted by the CIA in Washington last week. Among the guests of honour, fittingly, were Robert Lamphere and Meredith Gardiner.Reuse content