In the authorised Miss Marple continuation short story The Open Mind, Sir Aaron Kahn is a friend of Miss Marple who collaborates with her in the solution of the crime in the story.
Sir Aaron is a retired judge and honorary fellow of St Bede's College, Oxford. They had previously worked together to successfully solve a difficult case "The Quaverley choir murders" which had the police baffled. At the conclusion of the case, Sir Aaron invited Miss Marple to celebrate their success at high table at the Founder's Day Dinner at St. Bede's College. What happened at the dinner forms the main plot of the story.