[3] It is based on the Italian manned torpedo attack which seriously damaged the two British battleships Valiant and Queen Elizabeth and the oil tanker Sagona at the port of Alexandria in December 1941.

The film had a Royal Gala Premiere on 4 January 1962 at the Odeon Leicester Square in the presence of Princess Marina, Duchess of Kent.

The producers wanted John Mills to play the captain and asked Baker, "to contact him because we'd made so many pictures together.

And, although the screenplay is adapted from a French stage hit, "the usual lower deck humorists are there to kill off whatever suspense has been achieved.

As for the somewhat intermittent ethics of the subplot, not all John Mills's wrinkled concern nor Robert Shaw's manly distress makes their moral problem for a moment convincingly seaworthy.