Howard Florey was born in 1898 in Adelaide, South Australia, the third child and the only son of Joseph Florey, who had migrated from England to South Australia in 1882, and his second wife, Bertha Mary Florey (nee Wadham), who was born in Australia. In 1926, he married Mary Ethel Reed, who had been a fellow medical student at the University of Adelaide, and they had a son Charles and a daughter Paquita. Florey's first wife died in 1966 and in 1967 he married the Honourable Dr Margaret Jennings, an erstwhile colleague in his Oxford laboratories.
Florey graduated MB BS at the University of Adelaide in 1921 and went as Rhodes Scholar to the University of Oxford, where he studied in the honours physiology school and was much influenced by Sir Charles Sherrington. From Oxford, Florey went to Cambridge for a year and then spent a year in the USA as a Rockefeller Foundation travelling fellow. After a short period at the London Hospital, he returned to Cambridge, where he took a PhD degree and came under the influence of the biochemist Sir Frederic Gowland Hopkins, then at the height of his career.
In 1931, Florey was appointed professor of pathology at the University of Sheffield and 4 years later he moved to a similar post at Oxford University. This was a milestone in the history of pathology in Britain, because for the first time a man trained in experimental physiology and looking at pathology with a physiologist's eye came into a position of influence in the subject. Florey remained professor of pathology in Oxford from 1935 until 1962, when he resigned to become provost of Queen's College, Oxford.
Although he made notable contributions to many fields of experimental pathology, by far his most influential contribution to science, which made a lasting impact on both medicine and the health of mankind, was the development of penicillin as a systemic antibacterial antibiotic, suitable for use in man.
Florey had long had an interest in natural antibacterial substances, and in 1930 he began a study of the antibacterial properties of lysozyme, an enzyme that had been discovered in 1921 by Sir Alexander Fleming. Recognising the need for biochemical expertise for this work, Florey recruited EB Chain, a young refugee from Nazi Germany then in Hopkins' laboratory, who moved to Oxford in 1935. In 1938 and 1939 Florey and Chain jointly initiated a systematic investigation of the biological and chemical properties of the antibacterial substances produced by bacteria and moulds. They selected Fleming's ‘penicillin’ as the first substance to be studied in detail. It proved so promising in experiments in mice with streptococci, staphylococci and gas gangrene organisms, that all the resources of the Oxford laboratory were swung to its production on a scale that would allow clinical trials to be carried out. Thanks to the variety of skills possessed by the scientists Florey had gathered around him, developmental work proceeded rapidly. However, in spite of efforts to increase the yield from the cultures of Penicillium notatum, it was necessary to process 2,000 litres of culture fluid to obtain enough penicillin to treat a single case of sepsis in man.
Industry in wartime Britain could not produce supplies of penicillin in the amounts so urgently needed, and Florey and his colleague Heatley went to the USA to stimulate interest in its production there. Florey's enterprise and the perspicacity of the American pharmacologist Dr AN Richards, with whom Florey had worked in 1929 and 1930, were responsible for the production of penicillin in sufficient quantities for the treatment of casualties arising from the invasion of Europe in 1944. The development of penicillin has had a tremendous impact on medical practice, and opened the way for the great number of antibiotics that have since been produced.
After 1955, Florey returned to research in experimental pathology, working on the structure and function of the smaller blood vessels, the physiology of mucus secretion, and human reproduction, where he was interested in the movement of spermatozoa in the female genital tract.
In Oxford, Florey built up a stimulating atmosphere, which led to close contacts between different members of the department, who had been selected to cover a wide range of scientific disciplines. Not only was this spirit of collaboration all important in the early work on penicillin, but it resulted in the Sir William Dunn School being the leading centre of experimental pathology in Europe, through which a succession of able and brilliant young men passed.
In spite of the fact that he lived in Britain continuously after 1922, with a life centred on Oxford after 1935, Florey remained Australian in accent and outlook. In 1944, he was invited to Australia by prime minister John Curtin, to report on the Australian situation in medical research. It was on this visit that he was elected an Honorary Fellow of the College. His report had a catalytic effect on a group of Australians anxious to develop university research in Australia, which resulted in 1947 in the establishment of the Australian National University as a graduate university. Florey was very closely connected with the University for the next decade, as a senior adviser with a particular interest in the John Curtin School of Medical Research. He played the major role in establishing the School and in the construction of its building, and he visited the Australian National University for consultation almost every year until 1957. In 1965, he was appointed Chancellor of the Australian National University and resumed his annual visits to Canberra.
Florey's other great contribution to science was as president of The Royal Society. He was the tenth of a long succession of scientific physicians, of whom the last four were Sherrington, Hopkins, Dale and Adrian. He was the first Australian and the first pathologist to hold the office, and he proved to be an outstanding president. Not only did he produce, at a rapid rate, needed changes in the organisation of the Society, but he was responsible for obtaining for it splendid new premises in Carlton House Terrace.
In temperament Florey was reserved but sure of himself. He was insistent that any scientist in his laboratory should be adequately paid and have the best research facilities that he could obtain for him. He had no liking for speculation. For Florey, an idea was not worth having unless it could be used to help design an experiment which would, or could in principle, give a definitive result.
Florey was an enthusiastic photographer, and greatly enjoyed the extensive travelling he undertook after the War, at first as a result of the fame of penicillin and later because of his commitments in Australia. He relaxed with classical music, and in later life found pleasure in painting in oils, and in cultivating a rose garden in his home in Marston, outside Oxford.