With poxviruses my early and continuing scientific interest, I soon found that Derrick, who had trained with Alan Downie at Liverpool University, knew more about the history of vaccinia virus that anyone else in the world, and we conducted a long and protracted correspondence. I also visited him whenever I was in England for more than a few days, and we became and remain good friends.

Joel worked in the Smallpox Eradication Unit in Geneva for three years and in 1978 he accompanied me on a visit to China to check its eradication status. We have kept in touch ever since and I have occasionally collaborated with him to produce articles on smallpox. He is currently Director of the Fogarty International Center at US National Institutes of Health and we still exchange papers and emails on medical topics.

The Chanocks are my closest friends in the United States. Bobbie and I first got to know them well in 1972, on my second term as a Fogarty Scholar. He was a virologist and head of the infectious diseases unit in the NIH; they lived in a large house in Bethesda and apart from the periods when I was on a Fogarty scholarship I always stayed with them when in Washington. When I was there for prolonged periods as a Fogarty Scholar with Bobbie in 1973–74 and 1982–83, they also took us to concerts at the Kennedy Center and introduced us to the many exhibitions in the galleries in Washington, and were most loving and hospitable. They came out to Canberra at the time of my 80th birthday celebrations and Bob was one of the three speakers at the celebratory dinner.

Alan, Professor of Microbiology in the University of Liverpool, was the leading British expert on smallpox in the 1940s. I first met Alan and Nancy when I visited Europe in 1949 and always went to see him on later visits. Keith Dumbell and Derrick Baxby were among his students, all were experts on poxviruses. Alan and Nancy both came out to Australia and stayed with us in Canberra.

A PhD student with Alan Downie, Keith Dumbell became Professor of Virology at St Mary's Hospital Medical School and was the leading authority on variola virus during the smallpox eradication program. We met often at committee meetings in Geneva. After his wife died he married a South African woman and they went to Cape Town, where he was appointed Professor of Microbiology. I used to stay with them whenever I visited Cape Town and although he has now retired we still correspond regularly.

I have outlined the career of DA (as he is always called) in a ‘box’ in Chapter 16. Naturally, I saw a lot of him in Geneva throughout the campaign, and much more when I was writing Smallpox and its Eradication, for which he was the author of almost all the ‘operational’ chapters. He did this while carrying the heavy task of Director of the Johns Hopkins School of Hygiene and Public Health. I stayed with him and Nana whenever I visited Baltimore, and I was delighted when he and Nana came out here for my 80th birthday celebrations; he was one of the three speakers at the celebratory dinner and awarded me a unique accolade, Grand Master of the Order of the Bifurcated Needle.

I saw a lot of Zdeno, who was on the staff of the Smallpox Eradication Unit, in 1980–88, when I visited Geneva several times each year while producing Smallpox and its Eradication. He was a great help in going through the WHO Archives. From 1980–86 he had also been in charge of a major WHO study of monkeypox in Zaire, and in 1987 we collaborated in producing a small book, Human Monkeypox. In 1995, I was able to visit Zdeno and his wife Eva in their home in Prague, where he took me on a wonderful tour through that beautiful city.

I list him here, but Edgar was just a year ahead of me at Adelaide High School and the university, and I got to know him well when I spent three months in St Andrews College in Sydney in 1940 studying for the Diploma of Tropical Medicine, since he also boarded there. In 1963, he came to the JCSMR as electron microscopist. He was also a sculptor and made two sculptures for my garden. In 1967, he went to Phoenix, Arizona, and made a living as a sculptor, but left there a few years later to become Professor of Biology at the University of Hawai'i and lived on the Big Island in Hawai'i. I visited him there several times and he drove me everywhere. He retired to the mountains in Switzerland, where again I often used to visit him.

I had met Fred several times when he was at the Centers for Disease Control in Atlanta, and he was a Visiting Fellow at the JCSMR in 1970–71, but our close friendship dates from his involvement in the production of Veterinary Virology, the first edition of which was published in 1987. The chapters he wrote were excellent and his comments on those written by others very helpful, and after I had pulled out he supervised the production of the third edition in 1999. Our friendship was cemented by a week-long trip with him and his family through Yellowstone National Park in 1997, just after a meeting of the American Society of Virology in Bozeman, Montana. I have visited many interesting parts of the world, but none more exciting and unusual than Yellowstone, in such company. Very recently, he sent me a copy of his ‘Memoir’, a marvellous life story with superb colour photographs and a most illuminating text.