Vernon Sewell Director Gordon Wellesley Director Ralph Richardson Jaap van Leyden Actor Googie Withers Helène van Leyden Actor Esmond Knight Von Schiffer Actor Beresford Egan Krampf Actor Frederick Burtwell Captain Müller Actor Kathleen Byron Schoolmistress Actor Willem Akkerman Willem van Leyden Actor Dorothy Gordon Janni Peters Actor Charles Victor Bastiaan Peters Actor John Longden Jost Meertens Actor Joss Ambler Cornelis Smit Actor Margaret Emden Bertha Actor George Schelderup Dirk Actor Neville Mapp Joop Actor Ivor Barnard Admiral Actor John Carol Johann Actor Philip Leaver Chief of Police Actor Lawrence O'Madden Captain Schneider Actor Anthony Eustrel Lieutenant Wernicke Actor Charles Minor Bohme Actor Valentine Dyall Markgraf Actor Lieutenant Schouwenaar Captain of the U boat Actor Lieutenant Van Dapperen Lieutenant of the U-boat Actor John Arnold Navigator of the U boat Actor Michael Powell Producer Emeric Pressburger Producer