In the “Those That Will Work” section of Henry Mayhew’s London Labor and London Poor, published in 1861, there is a profile of Jack Black, whose self-appointed title was “Rat and Mole Destroyer to Her Majesty.” In addition to exterminating vermin royal and common, Black kept a collection of rats, which included a rare white one. Noting the white rat’s popularity with audiences, he bred it to sell the offspring; novelist Beatrix Potter is believed to have bought her albino rat Samuel Whiskers from the exterminator.