The son of Admiral Sir Gerald Charles Dickens and Kathlen Pearl Birch, Peter Dickens was born in Fulham in London in 1917. Dickens joined the Royal Navy as a naval cadet in September 1934, being promoted to midshipman in May 1935, when he was serving aboard in the Home Fleet. Dickens was acting sub-lieutenant in September 1937 and sub-lieutenant in May 1938 while serving aboard the Royal Yacht in Portsmouth. In 1940 he took part in the evacuation from Dunkirk.