The story
From Old English, recorded as Henehout in 1221 and Hyneholt in 1239. It means "wood belonging to a religious community", referring to the ownership of Hainault Forest, part of the larger Epping Forest, by Barking Abbey. The spelling was altered from the 17th century because of a false connection to Philippa of Hainault, the wife of Edward III.
Etymology from Wiktionary, CC BY-SA 4.0.