He continued his war service as chief staff officer to the First Sea Lord, as director of anti-submarine warfare and then as flag captain to the commander-in-chief of Home Fleet before becoming chief staff officer to the naval commander-in-chief of the Allied Expeditionary Force, taking part in the planning and execution of the naval operations for the Normandy landings.

[1] He joined the Royal Navy as a cadet in September 1908 and was promoted to midshipman on his appointment to the battleship HMS Conqueror on 15 May 1913.

[2] He joined the directing staff at HMS Vernon in July 1922 and, having attended the Royal Naval College, he was promoted to lieutenant-commander on 15 December 1924.

[2] Creasy served in the Second World War, initially as commanding officer of HMS Grenville, which was sunk off Kentish Knock in January 1940.

[2] He then transferred to the destroyer HMS Codrington, in which he led the rescue of Juliana of the Netherlands in May 1940 and then took part in the Dunkirk evacuation later that month.

He was appointed a Commander of the Dutch Order of Orange-Nassau (for rescuing the Crown Princess) on 12 May 1942,[11] and became flag captain to the commander-in-chief of the Home Fleet in the battleship HMS Duke of York in September 1942.

[12] Advanced to Knight Commander of the Order of the Bath on 1 January 1949,[19] he went on to be Vice Chief of the Naval Staff in November 1949.