Online Talk: Fantastic Beasts and Where to Find Them: The Search for Grindylow

In March 2025, Royal Mail issued a set of eight colourful stamps celebrating Britain’s ‘Myths and Legends’. Among them, representing ‘Northeast England’, is a figure resembling the ‘nursery bogey’ Jenny Greenteeth, a name used by parents to frighten children away from deep and dangerous ponds – but labelled ‘Grindylow’. Royal Mail seem to have adopted this unusual name because of its borrowing by J K Rowling and application to a species of malignant water-demons that infest the Black Lake at Hogwarts Castle.

However, Grindylow has an individuality and a folklore of her own, and in this talk we follow the paper trail of references from Hogwarts back, not to ‘Northeast England’ but to the vicinity of Manchester in the 1850s, and the works of local historian and pioneer folklorist John Higson. And also discover that Rowling was not the first author to misappropriate the name!

We shall consider Grindylow’s status and relationship to the better-known Jenny Greenteeth – and speculate about the origins of both names, and the nature of such water sprites. We shall also discuss the marl-pits of Lancashire, and why they should particularly have acquired demon guardians.

John Clark was for many years curator of the medieval collections at the Museum of London. Since retiring in 2009, he has continued research, lecturing and writing on a range of subjects, including medieval horses and their equipment, London legends, and folklore and fairylore. His book on the medieval story of the Green Children of Woolpit, The Green Children of Woolpit: Chronicles, Fairies and Facts in Medieval England was published in 2024 by University of Exeter Press.