With the end of the war, the scientists at Los Alamos, like millions of other people, started thinking about returning to their peacetime careers. Most of the seventeen British scientists were due to leave soon, so the British mission decided that they would give a farewell party for their American hosts. They planned it carefully: the wives would cook soup and turkeys for 150 people in their separate kitchens, and then rush them over to Fuller’s Lodge as soon as the communal meal was over and the dining-hall vacated. For dessert they would make trifle, a dish unknown to Americans, mixing it in vats.
The high point of the evening would be the entertainment: a British pantomime, Babes in the Wood, with the scientists as the babes and a security officer portrayed as the wicked witch. Among the other pleasures was to be Otto Frisch’s performance as an Indian maiden. Fuchs was not persuaded to play a part in the pantomime, but he volunteered to drive into Santa Fe to buy the drink for the party. He went just a few days before it was due to take place, on Tuesday, 19 September.
This time, he did not prepare papers for his Soviet recipients beforehand. Perhaps he was being more cautious, and did not want to risk anyone finding incriminating papers on him. He set out along the winding, empty road to Santa Fe, past scrublands and vistas of mesas and canyons, then pulled over to the side and wrote out his report for the Russians, sitting in his car.
He had worked out the present rate of production of uranium 235 and plutonium at the production plants at Oak Ridge and Hanford and he gave these figures — 100 kilograms a month and twenty kilograms a month respectively. This would give an idea of how many atomic bombs America could make. Since Germany and Japan were no longer the enemies, it seemed pertinent to tell the Russians this. He wrote down a few more details of the design of the two atomic bombs. He said a suggestion for a ‘mixed’ bomb using uranium 235 and plutonium was being considered.
Gold had flown out to Albuquerque by way of Chicago, and arrived at the rendezvous point at Bishop’s Lodge Road, on the outskirts of Santa Fe, at six o’clock. Fuchs, meanwhile, bought the drink and arrived twenty minutes late, apologizing. Gold got into the car, pushing the bottles aside, and they drove up into the hills just outside Santa Fe. As darkness came and they looked down on the twinkling lights appearing among the sand-coloured adobe buildings, Fuchs talked to Gold more fully than he had ever talked to him before.
Now Gold and everyone else knew about atomic bombs. Fuchs told Gold that he was awestruck by what had happened, and he was upset at the destruction that the bombs had caused. He said there was no longer a complete interchange of information between the Americans and British at Los Alamos. He told him that he was becoming anxious that the British authorities might locate his father and bring him to England. He was worried about his father’s health, but he was worried also that his father might inadvertently give away his Communist past.
He also said he expected to return to England either at the end of the year or early the following year. He said his sister Kristel would know when he returned, and Gold could find out from her. This time, he had worked out himself a method of contacting a Soviet intelligence agent in England, and he gave Gold the instructions. The rendezvous place would be a London underground station, Mornington Crescent. His contact should wait for him there on the first Sunday of each month, at eight o’clock in the evening. He should carry a bundle of books; Fuchs himself would carry a copy of Life magazine.
Eventually, Fuchs gave Gold the envelope with his report, and dropped him off near the centre of town, where he could get a bus. Then he drove back to Los Alamos with the wine and spirits for the party, to find that his friends were worried about him because he had been away so long. He and Harry Gold never met again. He still did not know Gold’s name.
Feynman suggested to Fuchs that instead of going back to England, where living conditions were difficult in the aftermath of the war, he might try to get an academic post in America. He should have no difficulty after his work in Los Alamos, he thought. But Fuchs turned down the idea. ‘Britain has been good to me. I feel I owe it to Britain to work there,’ he told him.
As he had betrayed Britain’s secrets and planned to go on doing so, one might see duplicity in his reply, but it is more likely that he was sincere and that any irony was unconscious. He really did appreciate the way he was accepted in Britain, and he was coming to feel that he belonged with British people. His activities on the part of the Soviet Union were locked away in that other compartment of his mind, where feelings of gratitude had no place. Certainly he seems to have given no thought to doing what he was instructed by the Communist Party to do when he crossed the German border into France in 1933, and return to post-Nazi Germany to contribute his skills to the rebuilding of the country, not even to the Communist Germany that was being created in the Soviet occupation zone.
The British party for the Americans was a great success. After this most of the British returned home, but Fuchs was invited to stay a few months longer, and he accepted. Genia Peierls and Mici Teller decided that before the Peierls left they would all have a two-week holiday in Mexico City, along with Fuchs. Fuchs agreed readily, and offered his car for the trip, but Teller begged off, saying that he had too much work to do. Mici said she would come anyway. Fuchs was due to visit the Montreal laboratory so they decided to start their holiday when he returned. They arranged to meet him at Albuquerque Airport, and begin the journey from there.
He was going to Montreal to meet two British civil servants who had gone to Canada on a recruiting mission. Prime Minister Clement Attlee had announced in Parliament the previous month that Britain would have its own atomic energy programme, and said: ‘A research and experimental establishment will be created covering all aspects of atomic energy.’ The two civil servants were recruiting people for this establishment among the British scientists in America and Canada. The man chosen to be its director was Professor John Cockcroft (soon to be Sir John), the head of the Montreal laboratory.
On the advice of Chadwick and Cockcroft, the civil servants offered Fuchs a senior position. He was excessively cautious about accepting, and wrote: ‘Before accepting any permanent appointment, I would like to be sure that this would not prevent me from leaving the establishment in a few years if I wish to do so.’ But the appointment was confirmed.
The holiday in Mexico was a happy one. Everyone was in a good frame of mind. The car’s big end broke on the way there, and they had to spend two days in the small town of Marfa, Texas. Fuchs wrote to a colleague: ‘We are sitting for two days in this Texas metropolis of 3,000 inhabitants whilst the car is being stripped to the bone and reborn to a new prime of life — I hope.’
After this hold-up, they decided that they would drive through the night to make up for lost time. The two men took turns driving, and the women took turns staying up to talk to the driver to ensure that he did not fall asleep at the wheel.
In Mexico City they did all the expected tourist things. Fuchs was an appreciative sightseer and seemed to enjoy it all. They sailed on flower-bedecked boats among the floating gardens of Xochimilco, they marvelled at the Basilica of Guadeloupe and at the piety of the Mexicans who made the pilgrimage there, they bribed a policeman who stopped them for a traffic offence. They disagreed over a bullfight. The Peierls wanted to go to one, Fuchs said it was cruel to the bull and the horses and he would not go, and Mici Teller supported him. So the Peierls went to a bullfight and the other two stayed behind.