Dickens joined the Royal Navy as a naval cadet in September 1934, being promoted to midshipman in May 1935, when he was serving aboard HMS Nelson in the Home Fleet.

[2] From June 1942, Dickens was the commanding officer of HM MTB 234 and the senior officer of 21st MTB Flotilla when, in August 1942, he was awarded the MBE for saving his mined ship through damage control, and the Distinguished Service Cross in December 1942 for attacks on enemy shipping.

In July 1943 he was awarded the Distinguished Service Order for skillful and daring attacks "in enemy coastal waters".

From April 1955 to January 1956 he was based at HMS President, a shore establishment, and was promoted to captain in December 1955 before being appointed Assistant Deputy Chief of Staff (Plans), Allied Forces Mediterranean (NATO) at Malta from October 1956 to January 1957.

Dickens was captain of Chatham Dockyard and Queen's Harbour Master and chief staff officer to Rear Admiral Beloe between March 1961 to February 1964, and served as naval aide-de-camp to Queen Elizabeth II from July 1964 to January 1965.