At 58, Mr Anthony Horowitz, who was awarded an OBE for services to literature this year, is one of the UK’s most prolific and successful authors and screenwriters. He is the creator of the Alex Rider teen spy series and of the long-running TV series Foyle’s War. He also wrote The House of Silk, the first new Sherlock Holmes novel approved by the Conan Doyle Estate. His eldest son, Mr Nicholas Horowitz, is 25, graduated with a first in history from Edinburgh University and is about to start a course on the financial side of film-making. Here, father and son talk to MR PORTER about how the younger Mr Horowitz’s sporting prowess has influenced his dad’s work, and the joy of a new white shirt.