Admiral of the Fleet Thomas Maitland, 11th Earl of Lauderdale, was a Royal Navy officer and peer. As a junior officer he saw action supporting the blockade of Algiers by Greek revolutionaries in July 1824 during the Greek War of Independence and then took part in an operation to land a naval brigade in Brazil to protect Pedro I, the Emperor of Brazil, in the face of the Irish and German Mercenary Soldiers' Revolt. He also took part in the Battle of Luchana, an operation to defend the Port of Bilbao on the north coast of Spain, during the First Carlist War.

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.