By 1979 John had been a trustee for the British Pregnancy Advisory Service for ten years and was beginning to feel that he was not contributing very much. His final resignation however was due to the BPAS decision to form an association with another abortion charity that advocated the legalisation of much later abortions. John was convinced that this would damage the hitherto respectable image of the BPAS and made his views clear to the committee. But his letter of resignation avoided mentioning this issue and gave tiredness and too many other activities as the reason. (The continuing success of the BPAS during the years following the merger showed that no harm was actually done.) John's farewell party left him in no doubt that he would be missed. Among other things he was given an inflatable rubber dinghy, accompanied by a card with a picture of him paddling across a lake to reach some otherwise inaccessible plant!Reducing his working hours to part time did not seem to make much difference to the amount of travelling John did. In 1979 he embarked on a long series of visits starting with Pakistan. There he gave a lecture at a conference on applications of nuclear physics. He discussed measurement of radon-1-, lead in teeth and the take-up of plutonium in rats. Then he did a lot of sightseeing even travelling up to part of the Khyber Pass where he could look down on very young armed Afghans representing the new Communist Government. While in Pakistan he stayed first with the brother and then with the father of Saeed Durrani, a co-researcher and good friend at Birmingham University. From Pakistan he flew to Egypt to stay with one of his old research students, Dr Kamal Effat, who later became a professor in Cairo and a director of the Egyptian Atomic Energy Establishment. Again, sightseeing took most of his time. From Egypt he went on to the annual conference in Vienna and then to Gorleben on the river Elbe. There an inquiry was being held on whether to use a major salt deposit for the disposal of processed nuclear wastes which were to be glassified and then placed in steel containers before burial. John found the strong local opposition to the scheme illogical but he never had time to make his point or to submit his written contribution as he was then engaged to go on to a conference at Newcastle.
Much as he loved travelling, even John admitted that this was rather a long trip and before he moved on to Egypt from Pakistan, he became homesick, wishing he was able to join Reinet in a trip she was making to visit me and my children in Bournemouth. But his interest in the laboratories and sights he saw soon revived him.
John also took regular trips to Vienna to attend the annual meeting of the International Atomic Energy Authority if he was available. His visit in 1980 led to an interesting new piece of work. While listening to one lecture on the effects of radiation on mice, he noticed an anomaly in a table shown on a slide. The figures that struck him as odd seemed to indicate that the mice with the lowest doses of radiation had lived longer than the unirradiated control mice. He decided that the controls had not been looked after properly and turned his attention back to the rest of the lecture. But later the same morning he noticed the same thing in a slide displayed by another lecturer. Neither of the speakers referred to these hiccups in their results as they were drawing conclusions from the higher doses. John puzzled over this effect and then suddenly had the idea that low doses of radiation might encourage some sort of immune reaction. Later on he had coffee with Stan Cohn, a physicist from America he had met before and had admired, and mentioned the problem. Cohn didn't comment on the immune system explanation, but said that as a research student he had found the same response to low doses of radiation in some mice he was using in an experiment but hadn't dared publish it.
Once he was back at home, John looked up a number of papers on irradiation of mammals and regularly found the same blip in the results and even found it among the causes of death registered among those survivors of the Hiroshima and Nagasaki explosions who had had the very lowest doses. The phenomenon had not been remarked upon in any of the papers, as each researcher had assumed that it was merely a random error in his own piece of work. The effect was later called radiation hormesis. The word "hormesis" refers to any stimulatory or beneficial effect induced by low doses of an agent that could not have been predicted by the extrapolation of the detrimental effects induced by high doses.
Even his quickly thought-out explanation looked good. In his research of old papers he turned up one which showed a quicker immune response to an injected foreign protein under the action of low levels of radiation and he became convinced that small doses did indeed stimulate the immune system of young animals by producing large numbers of mostly harmless aberrant cells at a stage when the immune system is developing the range of its response. This would imply that the background radiation to which we are all subjected is positively useful in helping to prime our immune systems. At higher doses the effect is lost as the in-cell repair mechanisms are overwhelmed by the amount of damage.
Over the next few years, John mentioned this discovery as if it were his own in several publications about radiation and risk. Looking at the literature, I don't think that he was the first to describe the phenomenon but he did discover it from first principles himself and he put forward a possible mechanism that has stood the test of time. He popularised the subject by describing it in papers, lectures and letters and eventually included a full discussion of it in his next book: this was a theory which needed no new experimental work, for it could be formulated entirely by looking at the data in previous studies, although many have done new experimental work on it since. Attempts to explain the theory to a wider audience left John disgusted with television as a way of providing scientific facts for general consumption. Over a period of five years he gave three television interviews on radiation hormesis. Not one of them was broadcast as given. Of a two hour interview he had given in his own sitting room, one single sentence was later used, inserted in an entirely different broadcast about the dangers of ionising radiation in such a way that it seemed that he was agreeing with the case being made. The news media had changed a lot since the 1930s when the Daily Express had asked him to check their article about his experiments with gas masks before publication.
In 1981, John did at last retire. He spent some time separating his activities into various strands in order to hand the work over to a number of different people. He thoroughly enjoyed his retirement party, revelling in the admiration of so many colleagues and friends, some of whom had come from as far away as Germany. Professor Hardwick finished his speech about John in Latin, with the quote about Wren seeing his monument all around him.
Retirement, although indubitably more relaxing, brought no sudden break in activity. John continued to visit the Physics Department regularly, taking a particular interest in work he had started a few years before on the measurement of radon gas at various locations throughout the country. Radium, a radioactive metal found in tiny traces in most rocks and soil, decays into radon, a gas, which is therefore given off wherever there are deposits of radium. Radon seeps up through the ground and the reduced ventilation in modern housing allows it to become quite concentrated in houses built above granite, which contains more radium than other rocks. This concentration didn't happen in earlier times, when a good through draught was required in a home to keep a fire burning. Although John had always believed in draught-proofing his own house, he now realised that good draught prevention could actually be dangerous in some parts of Britain. He thought that the accumulation of radon could be causing a few extra hundreds of deaths a year in Britain from cancers such as lung cancer and also suggested that if draught prevention improved further, these numbers of deaths might be doubled or trebled. He kept up his involvement in the work the department was doing on the absorption of cadmium and other undesirable elements by people working in certain industries and was given a two year consultancy, at £2000 a year, by the Medical Research Council, to carry on the work.
He also kept some work going outside the University. The Suffolk County Council had employed Professor D C Leslie of Queen Mary College, London, as a Consultant and he asked John to help him. He sent John a number of queries about radiation risks to which John sent full replies. Later he took part in the Dounreay enquiry of 1986 in a similar role. But he did also spend a lot more time at home and Reinet was delighted with this. Several times she mentioned that she had fallen in love with him all over again. The fact was that for the last twenty years, both of them had been permanently busy, and had hardly seen each other except when tired. With more time, John could once again show his gallantry and his kind, affectionate nature, help with a few household chores and lend an interested ear whenever it was needed. In her turn, Reinet threw herself into any flower-hunting holidays they went on with gusto, memorising the identifying details of the plants John was interested in at the time. She also provided a secretarial service for him whenever it was needed: typing out more of his articles and speeches gave her an ever greater appreciation of the breadth of his intellect.
John had another immediate use for some spare time and that was to service and extend his photographic equipment. His camera was getting a little the worse for wear: during the Canada visit, Michael Chamberlain had noted with amusement that he had mended it with a piece of sticky tape that had itself started life holding together a pair of Marks and Spencers socks. He had several ideas for new equipment and began to spend a great deal of time in his workshop following them up.
His first project was to build a wide-angle 3-D camera. He and Reinet were proposing to take Jane and her children to Zimbabwe to visit Reinet's brother Henry, and John wanted something suitable to photograph the Victoria Falls: an object a mile wide is difficult to snap with anything conventional. He bought two Russian wide angle lenses and set them in a panel. Then he bought three shutters from the stereoscopic society and interconnected two of them behind the lenses and the third to an eyepiece so that he could see what he was looking at when he pulled the trigger. He used the film holder from an old camera, extending it in length with metal plates and, as before, added a shoe for an electronic flash in case this should be needed for indoor scenes later on. The whole equipment was obviously heavier than a modern hand-held camera but this made it easier to keep still during operation and John was well satisfied with the stereoscopic pictures he obtained of the spectacular waterfall.
The next project was of more general use to him. His first camera had two interchangeable lens panels which he could slot into the front, one for very close work and one for more conventional distances. This involved a lot of fiddling about to get photographs for his collection because usually he needed shots using each panel for different views of the same plant. Now he set out to make a whole new camera for close-ups only. He started with his well-established collection of lenses and bits of old camera, but attempted to build the main body out of plywood. Surprisingly, this let a little light through and Reinet helped him by coating it with several layers of black paint. The resulting camera used just one pre-focused distance of five inches. There were two snap-up metal rods at the sides of the camera, five inches in length, and to obtain perfectly focused close-ups of any flower or butterfly he moved the camera forwards until the object was between the ends of the rods and pulled the trigger. The longer distance lens panel then stayed permanently in the other camera and took any other shots needed. This system increased the bulk of equipment which he carried everywhere, but reduced the time taken to photograph each plant.
In 1982 there was a new grandchild, John, David and Maria's second child. His birth followed a tragedy, for their first child, a baby girl, had died at the age of four days. A new Fremlin was an important event and John was delighted that this line of Fremlins now looked set to carry on. In 1986, John's brother Peter arrived and yet another cause for worry followed. Peter seemed dreadfully weak and when his mother at last persuaded her doctor that there was something wrong with him, he was found to have a mild form of muscular dystrophy. As with his other grandchildren, John took a great interest in their development, and loved to hear any details of things they had said or done.
There was still one part of the world John had never visited - Australia. To his delight in 1982 the Australian Institute of Physics invited him to their conference at Canberra and offered him a tour of Australia to follow. He prepared a lecture on the applications of nuclear physics to medicine describing the types of research used, pointing out how quickly totally new diagnostic methods could be evolved and giving an idea of the wide scope of the new fields. This he delivered at the conference and then at several different centres while touring the continent.
He met several old friends. In Canberra he stayed with an erstwhile student and his family, met his old professor, Mark Oliphant and also Claire, the widow of his old friend John Gooden. In Sydney he again met old colleagues and even found a Fremlin relative.
In Brisbane he stayed with Brian Thomas and his family. Brian had been one of John's PhD students in Birmingham, working on and developing techniques for measuring cadmium and lead in people's bones. While in Queensland, John was very keen to see the Great Barrier Reef and although it was not the tourist season, Brian helped John to get a room on Brampton Island, a sort of satellite reef of the Great Barrier. John took himself on walks around the island, thoroughly enjoying all the wildlife and chased crabs to photograph them. He tried to book a trip in one of the glass-bottomed boats he saw advertised but these did not seem to be operating out of season and eventually he gave up and decided to try a swim instead. The strip of sea between Brampton Island and the mainland had a rapid tidal flow which was said to be dangerous, but the dead times between these flows were known and John chose his time carefully. He walked along the beach to the mid-point of the narrows, dumped his shirt, shorts and towel on the sand and went into the sea in his underpants and a mask. There were plenty of fish which shot away when he approached. He found a fine colony of small fish in a hollow between rocks about three or four feet down into which he could swim, to the active disapproval of the fish. Not wanting to be caught by the tide, he swam and waded back to shore to find that he had already been carried much further than he had thought and had time to worry that his pile of clothing had been removed by someone before he eventually found it.
One of the things that had increasingly concerned John over the years was that many people who were frightened by tiny risks from radiation didn't seem at all frightened by much larger risks in their daily lives. He began collecting data on the actual risks we encounter in all sorts of activities and produced talks and articles which compared these with the risks due to nuclear power production. These resulted in an invitation from the Institute of Physics to write a book on the subject. This, of course, created an enormous amount of work; for articles and talks he could choose to stick to material that interested him and to which he already had access; a book had to include a more complete survey. Reinet worked closely with John, looking up sources, copying tables and graphs and typing the text, tasks which afforded her a great deal of satisfaction. She found herself spending so much time on it that she gave up her work as Secretary for the Cystic Fibrosis Research Trust, becoming Treasurer instead which consumed less time. "Power Production What are the Risks" was published in 1985, but to John's dismay as an expensive hardback book only, when he thought he had made it clear to the publishers that a paperback edition was essential.
The book started with a discussion of risk and attitudes to it and then went on to a section about the various causes of cancer, carefully quantifying each of them. The rest of the book was taken up with a wide survey of the different types of power production showing the risks of accident and pollution at all stages. Although he counselled against making judgements based on worst possible cases John could not resist making up and including a few lurid stories:
"... it is perfectly possible for a couple of off-course fully fuelled Jumbo jets to collide, one of them crashing on Wembley stadium during a cup final, bits of it blocking the exits, and a hundred tons or so of kerosene - a litre each for 100,000 people - being scattered over the crowd and ignited, while the second Jumbo crashes on Canvey Island destroying the LNG (liquefied natural gas) storage tanks and a refrigerated supply vessel on the Thames just coming in with fresh supplies, all at a time when there is a suitable breeze to blow the cold gas down into Canvey Town with its thirty thousand inhabitants, before it explodes. There is more than enough LNG stored there to kill the whole population of Canvey and burn the entire town to the ground."He added several hypothetical serious nuclear accidents of extremely low probability, always with a demonstration of their limited effects.
John's feelings about chemical pollution had become very strong and he gave his views a thorough airing in the book. He reported some statistics produced in the mid 1970's, which he felt to be important. They showed large excesses of cancers, especially lung cancer and cancer deaths in urban compared with rural areas, which he believed must be caused by pollution, mainly from the internal combustion engine. Characteristically, having mentioned this, he then played it down by saying that smaller risks which could be influenced by future decisions were more important than these large risks that no-one would be prepared to do anything about. Nevertheless, he repeatedly pointed out how difficult it was to show reliably that any particular deaths were being caused by radioactive pollution as the background of cancer deaths is so high anyway. This was not to say that they did not happen, he said, for if dose rates are known, calculations of the probable numbers of cancers and deaths follow well-known statistical models.
He went on to mention another aspect of pollution which had been discussed in scientific circles for some years, but was not to become a subject for general discussion in Britain until after the great storm of 1987. The idea was that as fossil fuels were burnt, the level of carbon dioxide in the atmosphere would rise, and as its concentration increased, more of the sun's heat would be trapped within the atmosphere. This is known as the greenhouse effect because air containing an increased concentration of carbon dioxide acts rather like glass in that it allows the sunshine through but then traps the resulting heat. That atmospheric carbon dioxide levels have been rising since before the beginning of the twentieth century has been known for some time, and tiny, but steady rises in average world temperature over the same period make it look as if there is indeed a connection, but one tenuous enough to leave plenty of room for argument. John pointed out in his book that the increased energy in the atmosphere could lead to stormy conditions before excessive heating was noted, but again, within the normal vagaries of climate it was difficult to prove that this was already happening.
He made clear how important he thought chemical pollution to be by concluding:-
"If I have encouraged some of those who have worried about the tiny effects of nuclear wastes on our far distant descendants to worry instead about the thousands of our own children who are going to die in the world's big towns from the effects of pollution resulting from the burning of coal and oil, the work of writing this book will have been worthwhile."In 1986, after the book's publication, a serious accident did occur in the nuclear industry, at Chernobyl in the Ukraine, to the apparent delight of the media. John was rung up by two English journalists as soon as the news broke and asked whether an American newspaper's estimate of two thousand dead by radiation was more likely than the Russians' statement that only two were dead. John told them both that thousands could not possibly have been killed so quickly by radiation, whereas two could easily have been killed by the explosion, which turned out later to have been the case. All the newspapers that John saw the next day ignored his comments and reported the higher number. In fact twenty-nine firemen died fairly soon afterwards from the effects of radiation and eleven more died later while two hundred became seriously ill.
John made a careful collection of all the relevant facts as they were properly established during the weeks and months after the event and shortly afterwards he wrote an appendix about Chernobyl for the paperback edition of his book when it was at last produced. Then a couple of years later, when a second edition was suggested, John knew that it must be revised sufficiently to make room for an extensive discussion of Chernobyl. He also had a new collection of accidents associated with other power industries he wanted to include. Once more he and Reinet set to work, John finding that the more he looked at it, the more he discovered to need revising. He carefully described the incident at Chernobyl and listed the ways in which western reactors are different such that a similar accident cannot happen but he did also produce a list of special lessons he thought could be usefully learnt.
He agreed that the radiation from Chernobyl could be expected to lead to large numbers of cancer deaths in the future, in the next forty years between eight thousand and thirty-four thousand in the USSR and up to forty in the UK. But he felt these figures should be put into context: they would be difficult to find among the six million cancers in the USSR or the six million in Britain due to other causes during the same period. The most severe after-effect he could see from the incident was the disruption of the way of life of the Swedish Lapps who were stopped from selling reindeer meat by unnecessarily stringent limits which led in turn to millions of pounds worth of damage to Sweden's forestry plantations caused by rocketing reindeer populations. John suggested that the limit set, six hundred becquerels-2- per kilogram of meat would mean that a person eating a kilogram would increase his risk of cancer by as much as he would by smoking four cigarettes a week. The book's second edition came out in paperback in 1989.
Shortly after the Chernobyl incident, an interesting plan was proposed by Sir Frederick Warner, prompted by the heroism of the Russian firemen who had gone into the stricken plant. The idea was that the site of a nuclear accident should be explored first by elderly scientists carrying measuring devices, so that they could warn the emergency services and clear-up teams where the highest levels of radiation were and provide information to determine the length of shifts such personnel should be allowed to work. These scientists would be less likely to have their lives shortened by slow-growing cancers than younger people. To qualify to join this exclusive group of one hundred, a person had to be at least sixty-five, physically mobile and possess a skill or some knowledge that would be useful in a nuclear emergency. John was happy to volunteer to be added to the list but was never called upon to turn up for duty. He told one curious newspaper reporter that he ran a greater risk of suffering from the effects of fatigue or exposure while hanging about outside a plant with an ongoing crisis than of serious damage from radiation once inside it.