The Admiralty was the British government department responsible for the command of the Royal Navy until 1964, historically under its titular head, the Lord High Admiral – one of the Great Officers of State. For much of its history, from the early 18th century until its abolition, the role of the Lord High Admiral was almost invariably put "in commission" and exercised by the Lords Commissioner of the Admiralty, who sat on the governing Board of Admiralty, rather than by a single person. The Admiralty was replaced by the Admiralty Board in 1964, as part of the reforms that created the Ministry of Defence and its Navy Department (later Navy Command).
Before the Acts of Union 1707, the Office of the Admiralty and Marine Affairs administered the Royal Navy of the Kingdom of England, which merged with the Royal Scots Navy and the absorbed the responsibilities of the Lord High Admiral of the Kingdom of Scotland with the unification of the Kingdom of Great Britain. The Admiralty was among the most important departments of the British Government, because of the Royal Navy's role in the expansion and maintenance of the English overseas possessions in the 17th century, the British Empire in the in the 18th century, and subsequently.
The modern Admiralty Board, to which the functions of the Admiralty were transferred in 1964, is a committee of the tri-service Defence Council of the United Kingdom. This Admiralty Board meets only twice a year, and the day-to-day running of the Royal Navy is controlled by a Navy Board (not to be confused with the historic Navy Board). It is common for the various authorities now in charge of the Royal Navy to be referred to as simply 'The Admiralty'.
The title of Lord High Admiral of the United Kingdom was vested in the monarch from 1964 to 2011. The title was awarded to Prince Philip, Duke of Edinburgh by Queen Elizabeth II on his 90th birthday and since his 2021 death has reverted to the monarch. There also continues to be a Vice-Admiral of the United Kingdom and a Rear-Admiral of the United Kingdom, both of which are honorary offices.
The crew of HMS Troutbridge make multiple references to The Admira;ty.