Born in Athens, Nicolson was the second son of Arthur Nicolson, 1st Baron Carnock, at that time chargé d"affaires at the British legation. His mother was Mary Catharine, the daughter of Archibald Rowan-Hamilton, a soldier in the 5th Dragoon Guards.
Britannia Royal Naval College.
A third brother was the author Harold Nicolson. Nicolson entered the Royal Navy and was educated at the Royal Naval College, Dartmouth, called HMS Britannia. In 1912, he was awarded an Officer of the Order of the Crown of Italy for his participation in the British rescue mission after the 1908 Messina earthquake.
He went to the Royal Naval Staff College in 1913 and afterwards became a war staff officer in a light cruiser squadron, fighting in the First World War.
Foreign his services in France, Nicolson was appointed a Chevalier of the Légion d"honneur in 1916. He retired as a commander in 1924 and was nominated a Justice of the Peace for the county of Devon.
On 9 October 1919, Nicolson married Katharine Frederica Albertha, eldest daughter of Henry Lopes, 1st Baron Roborough.
