Guest Stars Joel Dommett as Himself Chris O'Dowd as Sir Barnes Wallis Joe Thomas as Alexander Graham Bell Joe Wilkinson as Dr. Doctor Bliss Alexander Armstrong as Sir Arthur Harris Samson Kayo as Bill Brett Goldstein as James Garfield Theo Barklem-Biggs as Guy Gibson Brian Quinn as Himself Sal Vulcano as Himself Matthew Steer as Charles Guiteau Tom Bennett as A.R. 'Dick' Collins Bruce MacKinnon as Charles Sumner Tainter Richard Glover as Railway Employee Lucy Middleditch as Librarian