Wartime thriller with film noir elements based on a true story as written in A.P. Scotland's autobiography "The London Cage". The plot has greatly exaggerated the actual events of A.P. Scotland's experiences, including the addition of a fictional love interest.
Three sailors get drunk while on shore leave and end up on the wrong ship. When they realise their mistake they scramble off it and onto their warship, HMS Ferocious. However, they soon realise that the vessel they have boarded is not the Ferocious but a German battleship.
Forever England gives John Mills his first leading role as Brown. Born after a brief affair between his mother and a naval officer, he joins the Royal Navy during the First World War. There his bravery and marksmanship keeps a German ship in port so a British ship can sink it. He becomes a hero, but at what cost?
Taxi driver Jim befriends Ruritanian child King Ludwig while the latter is on a visit to London. A plot is afoot by sinister forces to kidnap Ludwig, and Jim becomes caught up in the drama. After the child is abducted Jim uses all his ingenuity, including cross-dressing as a Countess and becoming involved in a car chase, to rescue him from his captors.