Roger Hermiston

Physicist Rudolph Peierls
Simon Davidovich Kremer aka 'Alexander Johnson'
Soviet agent Harry Gold
Spycatcher Jim Skardon


Tue 21st Jun 2022

Early in April 1941 at a party in Flat No 6 in the gleaming, white, ultra-modernist Isokon Building (otherwise known as the Lawn Road Flats) in London’s leafy Hampstead, there was an encounter between two men that would affect the course of the 20th century. It could also, if there had ever been tangible evidence it had taken place, have meant the hangman’s noose for one of the participants.

  The younger of the two was tall, thin, with round spectacles and a high forehead, and wore a serious expression on his face – looking every inch the PhD student he was. The other, with sharp-chiseled features and rather feminine eyes, appeared notably more relaxed despite a stiff, military bearing.

  The individuals concerned were German-born Klaus Emil Julius Fuchs, a brilliant 29-year-old theoretical physicist just released from an internment camp in Canada, and 40-year-old Simon Davidovich Kremer, former tank commander and now officially secretary to the military attaché at the Soviet embassy in London.

   They had one thing in common – they were both committed Communists with the interests of Stalin’s Soviet Union at heart. This was fine for Kremer, whose day job was official business for the Kremlin - although by night, as it were, he was a spy, working for Soviet ‘Fourth Department’ of military intelligence (the GRU).

  Fuchs, however, was doing everything he could to conceal his ideological beliefs from his British hosts. It was bad enough – but not surprising, given his nationality and the suspicions of wartime – that he had just spent six months in camps in the Isle of Man and Canada. But to have had his past Communist Party associations revealed would have put an end to application for British citizenship – and his hopes of an academic career in this country.

  The meeting between Fuchs and Kremer – although the latter introduced himself to Fuchs by his pseudonym, ‘Alexander Johnson’ – had been engineered by the flat owner Jurgen Kuczynski, ostensibly a well-respected economist, but in secret a prime mover in Communist party circles and, moreover, a leading recruiter of British spies for Stalin.

   Kremer, who spoke excellent English, purported to show an interest in science, and the two men chatted about the exciting potential of the atom. Such was their rapport that Fuchs was persuaded by Kremer to send him a short account of the potential of atomic energy, once he was back at his post at Edinburgh University.

  It’s not clear whether Fuchs realized Kremer was Russian, and that he was being set up as a possible agent for Soviet intelligence. If he did, he would surely have been very nervous. In April 1941 the Nazi-Soviet non-aggression pact was still in force, with Britain at war with both countries. Any aid to the enemy in wartime would be classed as treason, and punishable by the death penalty.

  As it was, Hitler launched Operation Barbarossa two months later which changed everything. The Soviet Union was now our ally, and when Kremer came calling at Fuchs’ door again in August, the latter knew exactly what the Russian was about – and had no hesitation in agreeing to spy for a country in whose system he wholeheartedly believed.

   That meeting in April 1941 was the first step on the road to Fuchs becoming the most influential spy of the 20th century, an accolade due him because he would eventually hand his new masters in Moscow the ultimate secret – that of the atom bomb. Not only that, he would even feed them some details of the next fearsome weapon of mass destruction, the hydrogen bomb, before his arrest in 1950 put an end to his treachery.

   The FBI developed an acronym – MICE - for assessing the motivations of traitors. M for the lure of money, I for ideological motives, C for reasons of coercion (ie blackmail) and E for ego, for the stimulating power of betrayal. For Klaus Fuchs read I and E; the unwavering belief in the Communist system, and – surprising to those friends who saw a generous, convivial, yet unassuming man – the satisfaction of being like a spider at the centre of the espionage web.

   If MI5 had bothered to get hold of Fuchs’s Gestapo file and read it when he fled to England in September 1933, it would have rung the loudest of alarm bells. Born in Leipzig, the son of a Lutheran pastor, Fuchs came from a notorious family described by one paper as ‘the red foxes of Kiel’ (Fuchs is German for fox), by way of both the colour of their hair and their politics. 

  Fuchs was involved in student politics early on, joining the Social Democratic Party and becoming a member of their paramilitary organization. Expelled from the party as his views moved further left, he joined the Communist Party of Germany – a dangerous move with the Nazis on the move and about to take power. Beaten by the Gestapo, and hunted down by them after the Reichstag Fire, he fled to these shores and found a place at Bristol University.

  Once in England Fuchs kept his politics very quiet and concentrated on making his way in the field of theoretical physics. He was quickly recognized as an outstanding talent and drawn into the group of scientists working on highly classified atomic research – which included Rudolph Peierls, a fellow émigré German.

   In March 1940 it had been Peierls, along with the Austrian Otto Robert Frisch, who produced the startling memorandum setting out, for the first time, how an atomic bomb (Peierls labelled it a ‘superbomb’) could be constructed from just a small amount of fissile uranium-235. Peierls thought very highly of Fuchs, and just a month after Fuchs had met ‘Mr Johnson’, he invited his protégé to join him in work ‘whose purpose I cannot now disclose’. Fuchs thus joined the team of scientists urgently working out the means to make an atom bomb – before Germany, with all its remaining outstanding physicists, got there first.

  It was the beginning of Fuchs’s eight year career as a prolific agent for the Soviet Union, the brightest and the best of all Stalin’s atom bomb spies. At first MI5 – as much concerned about his nationality as about his Communism, which they didn’t know the half of – were reluctant to grant him security clearance. But eventually they relented and Fuchs became a key member of Britain’s atom bomb project, codenamed Tube Alloys.

  When it became clear that war-ravaged Britain could not – financially and industrially – support an atom bomb venture to its conclusion, all the effort moved to America, to the Manhattan Project in the secret town of Los Alamos in the New Mexico desert.

    Fuchs moved there with the rest of the elite British scientists, and was soon making notes, drawing diagrams, compiling all the details he could on the development of the atom bomb for his America NKVD courier (by now it had bigfooted its junior organization the GRU to take control of Fuchs), Harry Gold, a 33-year-old industrial chemist. Testimony from Gold in later years would help bring down Julius and Ethel Rosenberg.

    Astonishingly, against all the rules of espionage, Gold often elected to meet Fuchs at the bridge over the river in the pretty Spanish-influenced town of Santa Fe. In broad daylight, just two hundred yards from the La Fonda hotel (which was stacked with FBI agents), Fuchs would be handing over crucial information about the implosion mechanism of the new plutonium bomb.

   ‘Trinity’ – codename for America’s A-bomb – was successfully tested in the Nevada desert on 16 July 1945. When President Truman told Stalin at the Potsdam conference a few days later that America now possessed a ‘new weapon if unusual destructive force’, he was surprised by the Soviet leader’s  lack of interest. But of course It was no shock to Stalin as Fuchs had been feeding him information about the A-bomb’s progress over the previous three years.

  America dropped its atomic bombs on Hiroshima and Nagasaki on August 6 and 9. The world was taken aback four years later when the Soviets successfully tested their own A-Bomb in Kazakhstan, two or three years earlier than US scientists had expected. Of course Fuchs had contributed significantly to this success.

  Fuchs might well have got away with his treachery and ended his days garlanded by the scientific establishment and the British government, not just for his war work but for his efforts post-war in advancing Britain’s new nuclear industry. He would very likely have been Sir Klaus Fuchs.

   But the Venona project, the successful decrypting of thousands of messages sent home by Soviet agents in America in the 1940s, eventually unmasked him. In 1949 he was clearly identified as the agent codenamed CHARLES in the decryptions – one message, dated 10 April 1945, calling CHARLES’S information ‘about the atomic mass of the nuclear explosive’ being of ‘great value’.

  In early 1950 MI5 put Fuchs under 24-hour surveillance, tapping his phones at home and at his workplace at Harwell atomic energy research establishment, and dispatching ‘watchers’ to follow him everywhere. He gave nothing away, until the avuncular, dapper, pipe-smoking former policeman Jim Skardon, MI5’s key interrogator, sat down with him.

    On Tuesday 24 January, in his fourth interview, Fuchs finally broke and confessed to Skardon. ‘I still believe in communism, but not as it is practiced in Russia today’, he declared. In the days and weeks that followed one objective was to protect his sister Kristel, who lived in Boston and had been aware – peripherally - of his spying activities.

    Klaus Fuchs was tried at the Old Bailey on 1 March 1950. He was convicted on four counts of espionage and sentenced to 14 years’ imprisonment, the maximum for espionage at that time. If that meeting in April had been part of the prosecution’s evidence – aiding an enemy in wartime – he might have been face-to-face with the public executioner Albert Pierrepoint, rather than facing the walls of a cell in Wakefield prison.

   Fuchs was released on 23 June 1959, having had one third of his sentence reduced for good behaviour. Returning to East Germany to a hero’s reception, he continued his work on nuclear research, right at the very top of the country’s scientific establishment. Amongst many accolades, he was given the Patriotic Order of Merit and the Order of Karl Marx. He died in East Berlin on 28 January 1988, aged 76.

   It is said that that a lecture Fuchs gave to Chinese physicists shortly after his prison release helped that country to develop its first atomic bomb, the 596, in 1964 – becoming the world’s fifth country to possess nuclear weapons, in an increasingly dangerous world.