Kingdom Swann is a talented but rather naive Scottish artist who lives in Edwardian London with his housekeeper, Violet, a dowdy and self-effacing but very loyal young woman from Lancashire. He is dismayed to find that there is no longer a demand for his style of paintings. Then Violet buys him a camera from the local market stall. Helped by his unscrupulous new assistant, Cromwell Marsh, he soon transforms himself into "Kingdom Swann, Society Photographer" and is much in demand. When two younger sisters want him to take "artistic photographs" of themselves in the nude, Marsh hoodwinks Swann into specialising in "tableaux": photographic versions of famous paintings of nudes, using local prostitutes as his models. Marsh realises that he can make a great deal of money on the black market by secretly printing selected parts of these photos and selling them under the brand name "Gentlemen's Relish" to a supplier of pornography. Swann is completely innocent of what is going on. Violet, aided by a group of suffragettes who are demanding votes and equality for women, stumble on Marsh's scheme. In the process they discover that a fiery opponent of pornography who has aspirations of entering the House of Lords is actually one of the best customers of Gentlemen's Relish.