From the inception of the Medico-Social Research Board, we carried out studies of drug taking, including cigarette smoking and alcohol, among children in primary and secondary schools. In the 1970s there was no serious problem of illegal drug taking in Ireland, although about 10 per cent of school children had experimented with marijuana and an even smaller percentage, particularly in the inner city of Dublin, had used ‘uppers’, the amphetamine group of drugs, and ‘downers’, generally barbiturate sedatives. By far the commonest drug used by young people was alcohol, cider in particular. We organised a number of programmes to persuade the government to stop all advertising of alcohol and cigarettes in the media and to persuade young people not to start smoking.

In the nineteenth century in Ireland, when alcohol abuse was an even greater problem than today, Father Theobald Mathew introduced the concept of ‘taking a pledge’ not to drink alcohol. Father James Cullen founded the ‘Pioneers’ in 1898. Pioneers not only take a very solemn pledge but also wear a pin in their jacket lapel to show that they are total abstainers. While the ‘rounds’ system was very common in Ireland – a system by which everybody in a group was expected to stand a round of drinks – a pioneer is not persuaded to drink alcohol.

In the late 1970s a number of chemists’ shops were burgled and morphine and opium derivatives, such as Diaconal and Palfium, were stolen. From 1980, heroin was being imported into Dublin, and an epidemic of heroin injecting began in the inner city, where over half the population were unemployed. This heroin epidemic particularly affected young people of between fifteen and twenty-four. In 1982, when discussing this problem with Michael Woods, the Minister for Health at the time, I decided to ascertain how common the use of heroin was in Dublin.

In 1976 Dr Patricia Sheehan, a Dublin doctor, was talking to a mother who had a Down syndrome child. Down syndrome, a disorder in which there are three chromosomes number 21 instead of the usual two, is also called trisomy 21. It causes changes in appearance which gave the disorder its old name, ‘mongolism’, and usually causes mental retardation. The mother told Dr Sheehan that there were other girls who had attended her school, St Louis, in Dundalk, Co. Louth, in 1956/57 who also had Down syndrome babies and that the mothers were young when the babies were born.

Patricia Sheehan decided to investigate the story and spent the next eighteen years finding out what had happened to the 178 girls who were attending the school at that time. She was able to trace 159 of them, 89 per cent, and questionnaires were completed by them and returned. She found six of the mothers had given birth to Down syndrome babies. Patricia Sheehan and a microbiologist, Professor Irene Hillary, published an account about this cluster in the British Medical Journal in 1983. In a follow-up letter, the number of girls at the school in 1956/57 reported to have had Down syndrome babies increased to eight.

In October 1957 there was a fire at Windscale, now Sellafield, the nuclear power and reprocessing station which is across the Irish Sea from Dundalk. At about the same time as the fire, there was also an influenza epidemic which affected many people in Dundalk, including girls at the school. The question was raised: was radiation from the fire at Windscale responsible for damage to the ova of some of the children attending the school, which had caused them to give birth to a child with an extra chromosome 21.

After the Chernobyl disaster in 1986 there was greatly increased concern about the possible effects of radiation on health. This was made more acute by the reported increase in leukaemia in Cumbria around the Sellafield site. In Ireland it was feared that not only Down syndrome, but various forms of cancer and other disorders might be due to radioactive material escaping from the reprocessing plant in Cumbria.

The view of Cape Town nestling under Table Mountain when I arrived on the Priam on 24 June 1947 confirmed the words of Francis Drake. At that time, Cape Town was a relatively liberal city. Jan Smuts was the Prime Minister of South Africa and the leader of the United Party, which mainly represented the English-speaking white population, descendants of British settlers. The opposition Nationalist Party represented the Afrikaner white community, who predominated in the rural areas, but Afrikaners had also moved into the cities. Descendants of the Boers, they spoke Afrikaans, a dialect of Dutch. In 1947, the white population was 2.4 million. There were also people of mixed race in the Cape, known as the Coloureds, descendants of early white Dutch-speaking settlers and their Malay and Hottentot (Koi) slaves; they spoke Afrikaans. There were a million Coloured people in South Africa, a third of a million Asian, mostly of Hindu origin and living in Natal, and seven million black or, as they were known at the time, Bantu (‘Bantu’ meaning ‘the people’). Democracy was restricted to the white population. When the early Dutch settlers first came to South Africa in 1652, the native people of the Cape were the Hottentots. The Bantu people, at that time invading from the north, had reached the border of the Cape Province at the Fish River but not the Western Cape.

On the day we docked, the ship's officers decided to take the unattached ladies from the ship to dinner. We wandered around the streets of Cape Town and found what appeared to be a pleasant place for supper. When we sat down, we were told that only drinks were served and so we decided to leave. The proprietor, a Portuguese, then told us that we could not leave without paying an entrance fee of £2 per head. There were fourteen of us. We continued to argue, but the manager would not let us to leave and locked the door! It looked to me as if we were going to have an unpleasant quarrel and perhaps a fight because some of the waiters had put on knuckle-dusters.

On returning to Liverpool in September 1945 I found life very dreary; it was a great anti-climax after the excitement of Water-beach and Bomber Command. Rationing had become worse; even bread was rationed. Nonie was pregnant again. We found a first-floor flat at 29 Ullet Road, near Sefton Park, and I bought a 1939 Morris 8 from Nonie's brother Brian for £120. There had been remarkably little inflation during the war because of the government's tight control of prices and wages. Nevertheless, great social changes had occurred. The poor people in Liverpool were better fed than they had been before the war because, as a result of food rationing, price control and work for all, everyone could afford the limited rations and, for children, there was a free issue of milk. We were able to afford a live-in maid at a salary of £1 per week and, since her father had retired from practice after the war, Nonie had a relatively easy life. Nevertheless, there was general gloom from the strict rationing of food and clothes.

I called to the medical school to see Professor Tom Davie, the professor of pathology, who had been appointed Director of Post-War Medical Establishments. Although it was not immediately apparent, Britain was moving rapidly towards a National Health Service and, in order to help re-establish discharged doctors from the services, additional registrar posts had been made available at the teaching hospitals at a salary of £600 a year, paid by the state. I was fortunate to be appointed medical registrar to Robert Coope with whom I had worked in 1942 at Broadgreen Hospital. He was a consultant physician at the Liverpool Royal Infirmary.

As more and more doctors were demobilised and given registrar posts, the number of registrars at the Royal Infirmary was two or three times what it had been before the war, and so the amount of work for each doctor was not great. Once again I went back to the study of medicine; my enthusiasm had been increased by the encouragement I had received from Cony while I was in the RAF. I also attended the dramatic ward rounds of Henry Cohen.

I have already described how my interest in the cause of multiple sclerosis (MS) arose when I first emigrated to South Africa. MS is the most common disabling neurological disorder of young adults in the western world. It seldom occurs before the age of fifteen or sixteen and reaches its peak prevalence in persons in their early thirties. The disorder is more common in women than men, afflicting about three females for every two males, and it is typically a disease of exacerbations and remissions. The nineteenth-century neurologist Jean-Martin Charcot, of the Salpêtrière Hospital in Paris, first gave a good medical account of the disorder in 1857 when he showed that its victims had plaques, or patches of hardening, scattered throughout their brains and spinal cords. He called the disorder sclerose en plaques. The plaques are caused by the loss of myelin, the fatty material that makes up the sheath covering the nerve fibre. When the myelin sheath breaks down, conduction along the nerve fibre is disrupted. It can be compared to the insulation around a telephone wire.

Often the first symptoms of MS are caused by patches of demyelination in the optic nerves, resulting in a blurring of vision in one or both eyes (known as optic neuritis). This visual disturbance may last for a few days or up to six weeks, after which the person's vision generally returns to normal. 35 per cent of men and 75 per cent of women who have an attack of optic neuritis will then go on to develop MS during the ensuing fifteen years. Because the plaques of MS occur anywhere in the central nervous system, they can cause sensory symptoms, such as loss of sensation in any part of the body, loss of muscle power, or ataxia – uncoordination of movement. When the ataxia is severe, it may result in what is known as ‘scanning speech’, a slow enunciation, with a tendency to hesitate at the beginning of a syllable or word.

In the account of my work after leaving South Africa, I have said very little about my private life. It is difficult to do so when immediate family and personal friends are alive. It is easy enough to praise and say good things about those we know, but not so easy to be objective. Nor is it easy to be dispassionate about the decisions I have made, good and bad, in my own life.

On coming to Ireland, Maria and I, Gordon and Elizabeth spent a year in a rented house and then, in 1970, bought a house in Donnybrook, very close to St Vincent's Hospital and University College, Dublin. It was within walking distance of Baggot Street and my office. The house cost £9,700, which I obtained by selling some of my South African shares. Gordon and Elizabeth first went to a local convent school and then, when Gordon was about seven, he went to a boys’ school, St Michael's, and Elizabeth to Mount Anville Convent.

Maria is Serbian. She is a loving and good wife. Settling in Ireland, where she at first did not know anyone, must have been difficult for her because I was away a great deal attending conferences, undertaking research, and representing Ireland on the EEC committee on epidemiology. Fortunately, she has an outgoing personality and soon made many friends.

In London we often met Maria's friends from her schooldays in Belgrade. I was told how, during the German occupation, she would steal candles from the Catholic church and sell them; then with some of the money, she and her friends would buy loaves of bread and throw them over the barbed wire to the Yugoslav Jews and gypsies who were kept in an enclosure, open to the sky, in the town square, before being sent to camps where most of them died. From all I heard, Maria was the most popular girl in her class at school.

Whenever I saw a patient suffering from porphyria variegata, I interviewed all the relatives I could find, examined them for porphyria and drew up a family tree. In this way I was able to find out from which side of the family porphyria had been inherited. All the families I studied came from Afrikaner, or Boer, stock. It was possible to trace the ancestors from the family bibles and from the baptismal records of the Dutch Reformed Church. The way the Afrikaners named their children was also a great help; the first son was always given the names of the father's father, the second son those of the mother's father, and the third son the father's own names. The first daughter was given the names of the mother's mother, the second those of the father's mother, and the third the mother's names. This meant that the first-born uncle would have the same names as the great-grandfather. I was able to trace the families on the affected side back about 150 years, to the early part of the nineteenth century. After a great deal of research, I traced 32 family groups to their ancestors back about five or six generations.

Tracing the porphyric families to earlier than the nineteenth century was made easier by research carried out by Christoffel Coetzee de Villiers, the editor of the Het Volksblad newspaper, in the 1870s and 1880s. He found the names of the ancestors of his own family and those of most of the old Boer families from their baptismal records back to their ancestors who had come from Europe, many in the latter half of the seventeenth century. When he died in 1884, de Villiers's register of the old Cape families was published in three volumes. Dr J. Hoge studied the families of the early German settlers, while C.G. Botha made a careful examination of French Huguenot refugee families who had come to the Cape about 1688.

In August 1943 I received my call-up papers to join the Royal Air Force as a medical officer with the rank of flying officer. This rank was equivalent to that of a first lieutenant in the army. The newly recruited doctors first reported to a training centre where there were about ten other doctors who had been conscripted at the same time. We were given a week's preliminary training: how to salute, how to march reasonably in step and the structure of the RAF. Since I had been in the Officer Training Corps at Ampleforth, this was straightforward.

After a few days of basic training, we were sent to a large air force station at Halton, Buckinghamshire, to learn something about aviation medicine and tropical medicine. In order to impress on us how important it was to use oxygen, we were put into a decompression chamber. As the atmospheric pressure was lowered, we were asked to do simple sums, such as 13 take away 6. I wrote down the wrong answer. I remember little after this until I woke up on the floor of the decompression chamber, the sergeant in charge having plugged in my oxygen mask. We were not likely to forget the importance of using our masks. On another occasion an aeroplane flew overhead and dropped an irritant gas, such as is used to disperse a crowd, so we quickly appreciated the importance of always carrying our gas masks. Fortunately, poison gas was never used in the Second World War.

The officers’ mess at Halton had formerly been a palace belonging to the Rothschild family. There was a magnificent hall in which we normally took afternoon tea. After I had been at Halton about ten days, I was talking to my friends in the hall while having tea and was leaning negligently against one of the tables.

Towards the end of 1985, when I was about to retire as director of the Medico-Social Research Board, I was asked by the medical adviser of the Agricultural Institute of Ireland, Dr Alan O'Grady, if I would undertake a study on the cause of death in men in the research and technical staff at the institute, because there appeared to be a high number of deaths from cancer among them before they reached retirement age.

The national agricultural research organisation, now renamed the Agriculture and Food Development Authority, has its headquarters in Dublin and has seven major centres. The research programme carried out at the centres covers a broad spectrum of activities relevant to the agricultural industry. The director of the institute, Dr Pierce Ryan, through the personnel officers, provided me with a list of the research and technical workers who had died while still working at the institute and a breakdown of the work-force by age. I obtained copies of their death certificates and their hospital records. The work and medical histories of those who had died were also obtained from the personnel officers’ records.

There had been, in the previous twenty years, twenty-one deaths among the research and seven among the technical staff, all men; eleven of the twenty-eight deaths were from cancer. Four of the eleven cancer deaths were from primary brain cancers; three were from leukaemia, and one death was from Hodgkin's disease, a disorder related to leukaemia. There were also two deaths from abdominal cancers of unknown primary source, probably due to cancer of the pancreas, and one from cancer of the stomach. Approximately one in thirty of all cancer deaths, or one per cent of all deaths, would have been the ‘expected’ number from primary brain tumours in males in the age-group 40–64 years. Leukaemia and lymphatic cancers are relatively uncommon cancers to cause death.