E. Cobham Brewer 18101897. Dictionary of Phrase and Fable. 1898.
When Charnel chapel, St. Pauls, was taken down by the Protector Somerset, in 1549, more than 1,000 cart-loads of bones were removed to Finsbury Fields, where they formed a large mound, on which three windmills were erected. It was from these mills that the street obtained its name. (Leigh Hunt.)