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.

Admiral of the Fleet is a five-star naval officer rank and the highest rank of the Royal Navy, formally established in 1688. The five-star NATO rank code is OF-10, equivalent to a field marshal in the British Army or a Marshal of the Royal Air Force. Apart from honorary appointments, no new admirals of the fleet have been named since 1995, and no honorary appointments have been made since 2014.