Claim: Beau Brummell, Lord Alvanley, Henry Midmay, And Henry Pierrepont (dubbed "the Dandy Club" by Byron) jointly hosted a masquerade ball at Watier's private club (a gentleman's club located at 81 Piccadilly in west London) in July 1813–an event that marked Beau Brummell's downfall.
Evidence: This changed in July 1813, at a masquerade ball jointly hosted at Watier's private club by Brummell, Lord Alvanley, Henry Mildmay and Henry Pierrepont. The four were considered the prime movers of Watier's, dubbed "the Dandy Club" by Byron. Watier's Club was a gentlemen's Club established in 1807 and disbanded in 1819. It was located at 81 Piccadilly on the corner of Bolton Street in west London. The incident marked the final breach in a rift between Brummell and the Regent that had opened in 1811, when the Prince became Regent and began abandoning all his old Whig friends.