When Alexander Fleming enrolled at St Mary's Hospital Medical School in 1901, the school was in Paddington, a district of west London. St Mary's Hospital stood on Praed Street, close to Paddington station, and the area became the institutional center of Fleming's professional life.
Fleming had moved from Scotland to London as a teenager and spent four years working in a shipping office. After receiving a small inheritance from his uncle, he followed his brother's advice to study medicine. He entered St Mary's in October 1901, qualified with distinction in 1906, and won the University of London's gold medal in 1908.
Although Fleming initially considered surgery, work in St Mary's Inoculation Department drew him toward bacteriology. He studied under Sir Almroth Wright and remained associated with the hospital for most of his career. In 1928, it was in a laboratory at St Mary's, Paddington, that he noticed the mould-related inhibition that led to penicillin.
The school later became part of Imperial College London, but Paddington remains central to Fleming's story.