Who was Theresa Berkley?
She was a celebrated Victorian-age dominatrix who specialized in flogging and flaggellation. We don't know what she looked like, unfortunately - no photograph, drawing or portrait of her is known to have survived. (The image above is merely a photo-illustration of some unknown Victorians engaging in erotic spanking.)
But we do know a little something about Theresa's livelihood.
The great pervert Henry Spencer Ashbee (aka "Pisanus Fraxi") wrote in his landmark pornographic reference work Index Librorum Prohibitorum:
The queen of her profession was undoubtedly Mrs. Theresa Berkley, of No. 28 Charlotte Street, Portland Place; she was a perfect mistress of her art, understood how to satisfy her clients, and was, moreover, a thorough woman of business, for she amassed during her career a considerable sum of money...
"Her instruments of torture were more numerous than those of any other governess. Her supply of birch was extensive, and kept in water, so that it was always green and pliant: she had shafts with a dozen whip thongs on each of them; a dozen different sizes of cat-o'-nine-tails, some with needle points worked into them; various kinds of thin bending canes; leather straps like coach traces; battledoors, made of thick sole-leather, with inch nails run through to docket, and currycomb tough hides rendered callous by many years flagellation. Holly brushes, furze brushes; a prickly evergreen, called butcher's bush; and during the summer, a glass and China vases, filled with a constant supply of green nettles, with which she often restored the dead to life. Thus, at her shop, whoever went with plenty of money, could be birched, whipped, fustigated, scourged, needle-pricked, half-hung, holly-brushed, furze-brushed, butcher-brushed, stinging-nettled, curry-combed, phletbotomized, and tortured till he had a belly full.
She also invented the Berkley Horse, an automatic flagellation machine still used in some S&M parlors to this very day.