Defence Council of the United Kingdom in the context of "Head of the Armed Forces"

The Board of Admiralty (1628–1964) was established in 1628 when Charles I put the office of Lord High Admiral into commission. As that position was not always occupied, the purpose was to enable management of the day-to-day operational requirements of the Royal Navy; at that point administrative control of the navy was still the responsibility of the Navy Board, established in 1546. This system remained in place until 1832, when the Board of Admiralty became the sole authority charged with both administrative and operational control of the navy when the Navy Board was abolished. The term Admiralty has become synonymous with the command and control of the Royal Navy, partly personified in the Board of Admiralty and in the Admiralty buildings in London from where operations were in large part directed. It existed until 1964 when the office of First Lord of the Admiralty was finally abolished and the functions of the Lords Commissioners were transferred to the new Admiralty Board and the tri-service Defence Council of the United Kingdom.

The Admiralty Board is the body established under the Defence Council of the United Kingdom for the administration of the Naval Service of the United Kingdom. It meets formally only once a year, and the day-to-day running of the Royal Navy is conducted by the Navy Board, which does not include any ministers.

The Admiralty Board was established with the abolition of the Board of Admiralty and the integration of the three service ministries into the Ministry of Defence.

First Sea Lord, officially First Sea Lord and Chief of the Naval Staff (1SL/CNS), is a statutory position in the British Armed Forces, held by an admiral or a general of His Majesty's Naval Service. As the highest-ranking officer in the Naval Service, the chief is the principal military advisor on matters pertaining to the navy and a deputy to the Secretary of State for Defence. The CNS is also 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. The post is currently held by General Sir Gwyn Jenkins.

Originally titled the "Senior Naval Lord to the Board of Admiralty" when the post was created in 1689, the office was re-styled First Naval Lord in 1771. The concept of a professional "First Naval Lord" was introduced in 1805, and the title of the office was changed to First Sea Lord on the appointment of Sir John "Jackie" Fisher in 1904. Since 1923, the First Sea Lord has been a member of the Chiefs of Staff Committee; they now sit on the Defence Council and the Admiralty Board.

The Navy Board is the body responsible for the day-to-day running of His Majesty's Naval Service. Its composition is similar to that of the Admiralty Board of the Defence Council of the United Kingdom, except that it does not include any of His Majesty's Ministers. The Board shares a name with its historic predecessor, the Navy Board of 1546 to 1832, but is unrelated in structure or membership.