However, he was actually born in "Green Arbour" (near the Old Bailey), London, the son of Francis Heydon (of Sidmouth in Devonshire) and Mary (née Chandler, of Worcestershire).
[1] He attracted attention in royalist and occultist circles for predicting the future, including the death of Oliver Cromwell, then Protector.
Their royalist connections caused both Francis and John Heydon to be imprisoned in the final years of the Commonwealth era.
[1] In 1665, Heydon published "Psonthonphanchia, or a Quintuple Rosiecrucian Scourge for the due Correction of that Pseudo-chymist and Scurrilous Emperick, Geo.
[4] He was referred to as "an ignoramus and a cheate" by Elias Ashmole; Frances Yates termed him a "strange character...an astrologer, geomancer, alchemist, of a most extreme type.