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