Harwell came to have two roles. It was a major academic research centre, producing original work for publication in the whole field of atomic physics, sometimes in co-operation with universities; and it was also providing the scientific back-up for a major industrial programme to create both atomic weapons and atomic power.
Fuchs had never worked on the physics of atomic power before, but he learned about it at Harwell, and contributed some new ideas on reactors. He also worked on safety, in conjunction with a number of scientists from the Medical Research Council, and helped work out permissible, or safe, radiation levels. He sometimes used to visit the MRC in London in company with one or two others from Harwell. On a couple of occasions, when they had time to kill before catching a train back to Didcot, they asked Fuchs to join them for a drink or a visit to a film, and he turned down the invitation, but he did not tell them what he was doing instead.
When he was discussing reactor safety once with Compton Rennie, he returned to the accident at Los Alamos which killed Louis Slotin, and which he had investigated as one of his last tasks there. He told Rennie to work out as an exercise just what had happened: why there was a release of radiation, how strong it would have been, why there was no explosion.
When the Theoretical Division had a colloquium to review work, he would sit in the front row, often encouraging the speaker if it was a junior member of the division, or throwing out an occasional useful question. When he himself gave a talk it was always well attended. He was not an entertaining speaker, but his lectures were packed with information clearly presented for a professional audience.
Professionally and socially, Fuchs belonged at Harwell, as he had not belonged anywhere since he left Germany. Always sure of his ability, he was now confident of his status also.
He was sufficiently confident to hit out when he clashed with Bretscher over work. The dispute was unusual for him but not for Bretscher, a man who was much liked but who none the less generated friction, so that a lot of his friends quarrelled with him on occasions. It arose out of a project to measure the amount of radioactivity that would be put into the Irish Sea by the Windscale atomic power complex that was being built on the Cumbria coast, a subject that is controversial today — the site is now called Sellafield. The man directly in charge of the project was Henry Seligman, who worked in Bretscher’s Nuclear Physics Division. Some people were sceptical about whether it was possible to get any useful answers at this early stage, so Seligman christened the project Seanuts. Fuchs was among the sceptics. When Bretscher and Seligman wanted a theoretical physicist to work with them, they approached John Scott, without going through Fuchs. Since Scott was in Fuchs’s division, this was a breach of etiquette and Fuchs was annoyed.
Seanuts overlapped Fuchs’s own studies on radiation and safety, and Fuchs came to feel that Bretscher was pushing through the project against the general interests of Harwell and for his own advancement, and putting pressure on Scott to produce figures. The argument escalated, to the point where Fuchs wrote Bretscher a letter of two and a half closely typed pages which sounds at times like a bureaucratic declaration of war. It contained sentences such as: ‘I strongly deprecate your attempts to hide behind Scott.’ And ‘I find it very surprising that you should force yourself into a leading position in the irradiation project against evident opposition.’ And ‘I shall resist any attacks which are made behind my back, and any attacks which are made for the purpose of prestige or position.’
Bretscher stormed off to Cockcroft with the letter, demanding a withdrawal from Fuchs. As usual, Cockcroft declined to throw his weight into the conflict, but it was smoothed over, and Fuchs did his bit to restore peace by inviting the Bretschers to tea in the garden at Lacie’s Court on a Sunday afternoon.
During all this time, he was writing his reports for his Soviet contact, and meeting him occasionally in pubs. But the gaps between these meetings became longer. Doubts about the Communist philosophy, and about what he was doing, were seeping into his mind on several levels, and they began to erode the diligence with which he was carrying out his self-imposed task on behalf of the Soviet Union.
Fuchs was becoming friendly with another man at Harwell, Henry Arnold, the security officer, his fellow guest at dinner that evening at the Bretschers’. Arnold took the lead in establishing the friendship. He wanted to get to know Fuchs for professional reasons. He had decided that if there was a spy at Harwell, then Fuchs would be high on the list of suspects.
This was partly because Fuchs’s obvious reserve could mean that he was hiding something. It was partly also because of a simple test Arnold ran soon after he came to Harwell. He told each of the division heads that, as security officer, he would like to have a duplicate key to each division’s safe. They all refused, as he expected, except Fuchs, who agreed readily. He decided that Fuchs might be too good to be true.
Arnold was unusual among security officers at such establishments in that he was popular with the scientific staff. He had not been professionally involved with security matters for most of his life. He had been a particularly adventurous fighter pilot during World War I, and then had led an unadventurous life for the next twenty years working at the Bank of England. He rejoined the RAF in World War II and served as a security officer, rising to the rank of Wing Commander. After the war he went back to the bank, but then was tapped for the Harwell job. He was a tall, thin, angular man with a jaunty walk, a ready smile and a quiet manner. He was a serious amateur cellist and the son of a concert pianist. As always among physicists, many people at Harwell were music-lovers or serious amateur musicians, and Arnold enjoyed talking about music with them. He used to drop in on people for a cup of tea or coffee and a chat, and hear the latest gossip about who was doing what. This was his way of keeping tabs on things.
At one party, when the drink was running out and what was left was not strong enough to suit some people’s idea of revelry, a few of them broke into a laboratory and purloined a flask of ethyl alcohol, which they added to some elderberry wine. They did not tell Fuchs, who was at the party, because they knew he would disapprove. Arnold was there, and could see what they were doing. Someone said to him, half-jokingly, ‘You won’t tell on us, will you, Henry? "It’s nothing to do with me,’ he said, jovially. ‘Theft from a laboratory is a police matter. I only get involved if you sell it to the Russians.’
Arnold decided that the most likely security risk at this time was someone motivated by an ideological belief in Communism. He had read and absorbed some of the Moral Rearmament Movement’s pamphlets on ideological conflict, with their emphasis on hearts and minds, and winning people over from the enemy camp. Much later, Arnold explained his attitude to the threat of espionage by an ideologically motivated Communist: ‘I decided that by friendship and trust, I had to endeavour to inspire an individual loyalty and affection, if it comes to that. If possible, I wanted to awaken the conscience — is that the right word? Yes, conscience, I think — in the minds of such persons, in contradiction to the dictates of the Communist ideology, in which there was no scope for the scruples of the individual conscience.’[14]
14
In a radio interview with me for a programme about Klaus Fuchs, broadcast by the BBC on 1 August 1977. — NM