basil sydney portrays BD and perfectly depicts why your species is doomed...,

wikipedia |  Michael Cannon (Richard Burton) returns to London after the Second World War and places advertisements in the personal column of various newspapers (The Daily Telegraph distributed miniaturised copies of the newspaper showing the 'ad' at U.K. cinemas after each performance of the film), in which "Biscuit" tries to get in touch with "Sea Wife". Eventually Cannon, who is Biscuit, receives a letter summoning him to the Ely Retreat and Mental Home. There he meets an ill man nicknamed "Bulldog" (Basil Sydney). Bulldog tries to persuade Biscuit to give up the search. A flashback reveals the backstory.

In 1942, people crowd aboard a ship, the San Felix, to get away before Singapore falls to the Japanese Army. Biscuit is brusquely shouldered aside by a determined older man (later nicknamed Bulldog) (Basil Sydney), who insists the ship's black purser ("Number Four") (Cy Grant) evict the people from the cabin he has reserved. However, when he sees that it is occupied by children and nuns, he reluctantly relents. The nun with her back to him is the beautiful young Sister Therese ("Sea Wife") (Joan Collins). Later, the San Felix is torpedoed by a submarine. Biscuit, Sea Wife, Bulldog and Number Four manage to get to a small liferaft. Only Number Four knows that Sea Wife is a nun; she asks him to keep her secret.

It soon becomes evident that Bulldog is a racist who does not trust Number Four. Later, they encounter a Japanese submarine whose captain at first refuses to give aid, but gives them food and water when Number Four talks to him in Japanese, though what he said is kept a secret between him and Sea Wife.

After nearly being swamped by a vessel that passes by so quickly they do not have a chance to signal for help, they eventually make it to a deserted island. When Number Four finds a machete, they build a raft. Number Four insists on keeping the machete to himself, which heightens Bulldog's distrust. Meanwhile, Biscuit falls in love with Sea Wife; she is tempted, but rejects his romantic advances without telling him why.

Finally, they are ready to set sail. Bulldog tricks Number Four into going in search of his missing machete, then casts off without him. When Biscuit tries to stop him, Bulldog knocks him unconscious with an oar. Number Four tries to swim to the raft, but is killed by a shark.

The survivors are eventually picked up by a ship, and Biscuit is taken to a hospital for a long recovery. By the time he is discharged, Sea Wife has gone.

Thus, he searches for her via the newspaper advertisements. Bulldog tells Biscuit that Sea Wife died on the rescue ship. Heartbroken, Biscuit leaves the grounds and walks past two nuns without noticing that Sea Wife is one of them. She watches him go in silence.