5 Pounds - Elizabeth II Alexander Fleming

Fleming's 1928 discovery of penicillin — famously attributed to a contaminated Petri dish left out before a holiday — was not acted upon clinically until Howard Florey and Ernst Chain developed a usable form in the early 1940s. Fleming received the Nobel Prize in 1945 alongside them, though he consistently deflected sole credit. Guernsey's connection to the subject is largely commemorative rather than biographical; the island has issued numerous five-pound crown-sized pieces under license tied to British anniversaries and scientific figures.