Short answers, pulled from the story.
Alexander Fleming, a Scottish physician working at St Mary's Hospital in London, discovered penicillin's antibacterial effect in 1928 after noticing a Penicillium mould killing bacteria on a contaminated culture plate. He named the substance penicillin on the 7th of March 1929.
Fleming lacked the chemistry background to isolate and purify the substance, and his 1929 paper attracted little attention. It was not until 1939 that a team at the University of Oxford, led by Howard Florey and including Ernst Chain and Norman Heatley, developed methods to extract, purify and test it.
Alexander Fleming, Howard Florey and Ernst Chain shared the 1945 Nobel Prize in Physiology or Medicine for the discovery and development of penicillin. Dorothy Hodgkin later won the 1964 Nobel Prize in Chemistry for determining penicillin's chemical structure using X-ray crystallography.
American researchers at the Northern Regional Research Laboratory in Peoria, Illinois, boosted yields by adding corn steep liquor and by identifying a high-yielding mould strain found on a cantaloupe in a Peoria fruit market in 1943. Pfizer then adapted deep submergence fermentation techniques, converting the Rubel Ice plant in Brooklyn into a full production plant that opened on the 1st of March 1944.
Albert Alexander, an Oxford policeman with a severe facial infection, was treated by Charles Fletcher starting on the 12th of February 1941. He initially improved but relapsed after the limited supply of penicillin ran out, and he died on the 15th of March.
Penicillin was first identified at St Mary's Hospital in London, where Alexander Fleming observed in 1928 that a Penicillium mould contaminating a culture plate was killing nearby bacteria. The mould was later reclassified, after decades of confusion, as a strain of Penicillium rubens.