Fleming was an Ayrshireman, educated at Kilmarnock Academy and St Mary’s Hospital, Paddington, where he qualified as a surgeon in 1906.
During World War I he served as a captain in the Army Medical Corps, where he had ample opportunity to understand the limited usefulness of antiseptics in the treatment of serious wounds. Even before the war, his main research work had been in the field of bacteriology; and he returned to his research unit after the war.
Fleming discovered penicillin in 1928 and started to study its antibiotic properties. It was to be 15 years before penicillin would be produced in commercial quantities. Fleming was knighted in 1944, and for his achievement he shared the Nobel Prize for Medicine in 1945 with the two men who developed it: Howard Florey and Ernst Chain.
A shy and modest person, Fleming said, ‘I did not invent penicillin. Nature did that. I only discovered it by accident.’
He did not patent his discovery, preferring that all would benefit from it.