John Graunt was a shopkeeper in 17th-century London who followed his own curiosity to a rather grand result. His work gave rise to the fields of demography and epidemiology.
Research:

Unearthed! In July 2026, Part 1
41:36

SYMHC Classics: Raincoats
39:10

Behind the Scenes Minis: Shoes, Shoes, Shoes!
30:14