John Ingles

In the short story The Adventure of the Dartmoor Bungalow (later, chapters 3 and 4 of The Big Four), John Ingles was a retired civil servant who lived in a suburb ("one of the most depressing") of South London. According to Poirot, Ingles might appear as nothing more than a man of mediocre intellect who has a house full of Chinese curios with which he bores his friends". In reality he knew more about the underground life of China than anyone else in England. Ingles provided Poirot with important background information about Li Chang Yen, the Number One or the brains of the Big Four.