The First Sea Lord is the professional head of the United Kingdom's Royal Navy and the senior naval officer of the Naval Service. Formally known as the First Sea Lord and Chief of the Naval Staff (abbreviated as 1SL/CNS), the position is a member of the Admiralty Board and the Defence Council of the United Kingdom. The First Sea Lord is responsible for the fighting effectiveness, efficiency, and morale of the Naval Service and reports to the Secretary of State for Defence.
The role originated in the early 18th century, though it was formally established as the First Naval Lord in 1778. It was renamed First Sea Lord in 1904 following the restructuring of the Board of Admiralty. Historically, the post has been held by a four-star admiral, typically an Admiral in the Royal Navy, appointed by the UK government.
The First Sea Lord works alongside the Second Sea Lord, who focuses on personnel and training, and other Sea Lords responsible for specific naval functions. Following the abolition of the post of Chief of the Defence Staff (Navy) in 1985, the First Sea Lord assumed the role of principal adviser on naval matters to the Secretary of State for Defence and the Prime Minister.
The position is based at the Ministry of Defence in London and is a key component of the UK’s military command structure. The First Sea Lord also serves as the UK Maritime Component Commander in certain operational contexts.
The title “Sea Lord” is unique to the British naval hierarchy and does not imply noble rank; rather, it denotes seniority within the naval command.