Geoffrey Layton Slack – known as the ‘father of UK dental public health’ – played a leading role in establishing the British Association for the Study of Community Dentistry and the specialty of dental public health. He was born in Southport on 27 March 1912, the son of Charles Garrett Slack and Gertrude Slack née Wild. He went to Croxton Primary, Terra Nova Preparatory School in Cheshire and the Leys School in Cambridge. He then went to Liverpool Dental School, gained his LDS in 1934 and started in private practice. Once the Second World War began, Geoffrey joined the Royal Army Service Corps. As a lieutenant colonel and assistant director of supply and transport for the 21st Army Group, he was part of Montgomery’s Allied Expeditionary Force in June 1944. He gained an OBE for playing a major role in the planning and organisation of Operation Overlord, the Allied invasion of north-west Europe. Following his demobilisation, Geoffrey joined the Northwestern Dental School in Chicago, gained its doctor of dental surgery (DDS) and an interest in microbiology. Next came an FDSRCS and Manchester’s diploma in bacteriology. In Liverpool he became a senior lecturer/consultant and head of preventive and children’s dentistry. Geoffrey was head-hunted by the London Hospital in 1959 as a professor of dental surgery. He headed conservative dentistry, child dental health and bacteriology. In 1964 Geoffrey became dean of dental studies. Child dental health was an exciting department, with many full-timers gaining seniority. With colleagues, Geoffrey arranged the first International Symposium on Child Dental Health at the London, attracting over 200 people. From children’s dentistry grew prevention, epidemiology and planning, so paedodontists became leading community and public health dentists, with Geoffrey to the fore. Asked by the Nuffield Provincial Hospitals Trust to examine the feasibility of population studies of dental health and attitudes, his team compared north and south populations in Salisbury and Darlington. Supported by sociological interviews by Nottingham University, he proved one could obtain viable dental and social data from random samples. Geoffrey persuaded the Department of Health and Social Security to sponsor an adult dental survey in England and Wales. He was dental director, aided by colleagues from Birmingham, Leeds and Newcastle universities. In 1964 Geoffrey established a dental health study unit, with some staff seconded from other departments. Honorary staff included Jack Bingay (the first director of the New Cross School for Dental Therapists), Tom Liptrott (the second director at New Cross), Don Norman (chief dental officer for Hounslow), Stanley Gelbier (from May 1967 chief dental officer in Hackney), Colin Cowell (senior dental officer at Unilever) and Colin Davis (director of Gibbs Oral Hygiene Service). Geoffrey was responsible for examining people evacuated from Tristan da Cunha after a volcano erupted. He undertook toothpaste trials for Unilever, Proctor and Gamble and Bristol-Myers and evaluated gum in Crete for Wrigley. For the World Health Organization (WHO), he conducted studies in European countries and established a diploma in public health course at the London for foreign dentists. In 1967 Geoffrey establish a department of dental public health. The six London schools established a committee, chaired by Geoffrey, to plan a course for the diploma in dental public health at the Royal College of Surgeons of England, each contributing to the teaching. His lecturer, Brian Burt, was the tutor. Geoffrey later established a London Hospital MSc course in dental public health, tutored by John Bulman then Aubrey Sheiham. With George Bowden, his senior bacteriology technician, he developed a mouse-caries model to study caries in children. In 1971 the Medical Research Council established a dental epidemiology unit at the London with Geoffrey as director, based on his considerable expertise in epidemiology and microbiology. They studied caries in teenagers and monitored changes in the microbiology of plaque on caries-prone tooth surfaces. The unit was among the first to propose a multi-flora aetiology rather than *S mutans* as a single pathogen for caries. Geoffrey had a long association with the Royal College of Surgeons of England, with an FDSRCS from its inception in 1948. He was elected to the board of the Faculty of Dental Surgery, dean in 1971 and initiated planning for a higher qualification in general dental practice. The College awarded him the 1960 John Tomes prize and the 1965 Charles Tomes lectureship. He was a member of the council from 1971 to 1977. Geoffrey was a sought-after adviser to the Department of Health, close confidante of its Chief Dental Officer George Gibb and a member of its standing dental advisory committee (chairman for six years), of the central health services council, the British Dental Association’s dental health committee and the General Dental Council and a consultant to WHO. He was an honorary consultant to the Army and a civilian consultant to the RAF. Geoffrey wrote or contributed to a number of books and papers in medical and dental journals. In addition to his CBE, he received a fellowship of the American College of Dentists, an honorary doctorate of odontology from the University of Göteborg and fellowships from the Glasgow and Irish surgical colleges. Geoffrey had a stern military appearance, but in the lab he relaxed, dropped his ‘stiff upper lip’ persona and treated staff as their favorite uncle. He financially supported Christmas parties and allowed seaside outings by ‘not noticing’ their absence. Geoffrey loved chocolates and Christmas cakes made for him by technician Eileen Bowden; his fondness for fruit cake was legendary. Everything had to be done properly. He travelled to the station by moped wearing leather boots, gloves and helmet. Once Jill, his daughter, was horrified when he arrived for a school open day in a loud check suit in green, ‘more like an off duty bookmaker!’ An administrative colleague said Geoffrey ‘was very charming and a real gentleman in all his dealings. It was a pleasure to see him at work.’ He played hockey for Lancashire (from 1933 to 1939 and then from 1945 to 1952), the North of England (1935 to 1939 and 1945 to 1952) and for the England XI (1938 to 1939). He also played badminton and squash. Golf was an enthusiasm until sailing came along. With his boat on the Medway, he competed in cross Channel races and captained his sloop to win a 24-hour sailing challenge on Windermere. He took fitness and healthy eating seriously: there was a swimming pool at home and Stanley Gelbier recalls lunchtime meetings when they shared sacks of oranges. In March 1939 Geoffrey married Doreen Percival Ball, some papers proclaiming ‘England hockey star marries Actress’. After the war, they adopted Jill and Susan. Geoffrey Slack retired to his native Southport, close to Royal Birkdale Golf Course. He died on 5 June 1991, aged 79 years, and was survived by his wife and daughters. A memorial service was held in London at All Hallows by the Tower. The London’s alumni established a memorial medal to be awarded annually to individuals who made outstanding contributions to the college.