Lady Euphemia "Effie" King is the wife of Sir Harry King. Like her husband, she started from humble beginnings, the two of them advancing in society as Harry, who is known as the Piss King and King of the Golden River builds his waste management business up into a multi dimensional enterprise. She prides herself on being a most proper lady, who is distressed by inappropriate or demotic language. She makes Harry change the sign over Harry's compound, "H. King – taking the piss since 1961" to "recycling nature's bounty". Similarly, when Harry branches out into the railway business she insists that the new railway company incorporate the phrase Hygienic in its title as this sounded more respectable. She also requires that all trains contain lavatory facilities, the first class car facilities rivaling the best hotels (Harry very expeditiously ensures that the waste is not dumped on the track but is contained on board the train for resale later). She was, however, dissuaded from having Monsieur Bidet's patent hygienic invention installed on the trains, except perhaps on the Quirm line. She is very upwardly mobile, insisting that Harry attend all the best functions and she is very pleased when Harry branches out of the waste business into the railway one because you can't talk about excrement around the dinner table in society but railways are another matter.
Harry's pet name for her is "Duchess" which eventually comes true when Harry becomes Lord of the Permanent Way. Harry and Effie have several daughters, two of which, Daphne and Hermione, are named in the series. They also have grandchildren but they are not named as well as a favourite niece in Emily King who appears destined to marry Dick Simnel, Harry's partner in the railway business.