Grand Admiral a naval rank in one of the highest in the several European navies that use this system, what system are they using?
Military rank Military ranks are a system of hierarchical relationships in armed forces, police, intelligence agencies or other institutions organized along military lines. Usually, uniforms denote the bearer's rank by particular insignia affixed to the uniforms. Ranking systems have been known for most of military history to be advantageous for military operations, in particular with regards to logistics, command, and coordination; as time went on and military operations became larger and more complex, military ranks increased and ranking systems themselves became more complex.
Lieutenant of the Admiralty The Lieutenant of the Admiralty is a now honorary office generally held by a senior retired Royal Navy admiral. He is the official deputy to the Lord High Admiral, an office vested in Prince Philip, Duke of Edinburgh since 2011. He is appointed by the Sovereign on the nomination of the First Sea Lord.