 It is in the historic county of Middlesex.Forty Hill was recorded as "Fortyehill" 1610, "Fortie hill" 1619, "Fortee hill" 1686, named from "Fortey c.1350", that is ' the island (of higher ground) in marsh ', from Old English "forth-ēg" with reference to the slightly rising ground above the River Lea marshes.There have been houses in the road now known as Forty Hill since at least 1572.