Anthony Horowitz Creator, Writer Michael Kitchen Christopher Foyle Actor Lars Eidinger Karl Strasser Actor Jodie Hay Student Actor Charles Aitken Thomas Nelson Actor Rupert Vansittart Sir Alec Meyerson Actor Daniel Weyman Adam Wainwright Actor Mary Sheen Mrs. Jones Actor Jeremy Swift Glenvil Harris Actor Andrew Tiernan Geoffrey Helliwell Actor Honeysuckle Weeks Sam Wainwright Actor Tamzin Outhwaite Brenda Stevens Actor David Hounslow Parry-Jones Actor Richard Dillane Charles Roper Actor Tim McMullan Arthur Valentine, Dr. Trevelyan Actor, Actor Robert Donnelly Simmonds Actor Daniel Hill Headmaster Actor Colin Stinton Lt. Colonel Hoyt Jackson Actor William Armstrong Ray Donovan Actor Ellie Haddington Hilda Pierce Actor Fiona Button Mary Nelson Actor David Ryan Mr. Cranston Actor Paul Benzing George Gibson Actor Mark Huberman MI5 Guard Actor Karl Shiels American Major Actor Jill Green Executive Producer Jim Reeve Executive Producer Andy Hay Director