Admiral of the Fleet Lord John Hay, was a Royal Navy officer and politician. After seeing action in 1842 during the First Opium War, he went ashore with the Naval Brigade and took part in the defence of Eupatoria in November 1854 and the Siege of Sevastopol in spring 1855 during the Crimean War. He also took part in the Battle of Taku Forts in August 1860 during the Second Opium War. As a politician, he became Member of Parliament for Wick and later for Ripon. He was sent to the Mediterranean in July 1878 to take control of Cyprus and to occupy it in accordance with decisions reached at the Congress of Berlin. In a highly political appointment, he was made First Naval Lord in March 1886 when the Marquis of Ripon became First Lord of the Admiralty but had to stand down just five months later when William Gladstone's Liberal government fell from power in August 1886.

The First Sea Lord and Chief of the Naval Staff (1SL/CNS) is a statutory position in the British Armed Forces usually held by a four star admiral. As the highest-ranking officer to serve in the Royal Navy, the chief is the principal military advisor on matters pertaining to the navy and a deputy to the Secretary of State for Defence. In a separate capacity, the CNS is a member of the Chiefs of Staff Committee and, thereby, a military advisor to the National Security Council, the prime minister and the monarch. The First Sea Lord is typically the highest-ranking officer on active duty of the Royal Navy unless the Chief of the Defence Staff is a naval officer. Admiral Ben Key was appointed First Sea Lord in November 2021.