An excerpt from Filthy London.

Home to the Berkley Whipping Horse, a sort of saucy sandwich board that allowed for manual manipulation from the front and a beating from the rear. Its devotees were many, among them ‘mad’ King George IV. The device was designed for Theresa Berkley in 1828, a madam whose clientele was such that letters discovered after her death contained revelations so shocking that they ‘threatened the very fabric of society’. The Horse was later acquired by the Royal Society of Arts, for reasons unknown.