First Sea Lord
| First Sea Lord and Chief of the Naval Staff | |
|---|---|
| since 27 May 2025 | |
| Ministry of Defence Royal Navy | |
| Style | General | 
| Abbreviation | 1SL/CNS | 
| Member of | Defence Council Admiralty Board Chiefs of Staff Committee | 
| Reports to | Chief of the Defence Staff | 
| Nominator | Secretary of State for Defence | 
| Appointer | The Monarch On the advice of the Prime Minister, subject to formal approval by the King-in-Council | 
| Term length | Not fixed typically 3–4 years | 
| Formation | Senior Naval Lord (1689–1771) First Naval Lord (1771–1904) First Sea Lord (from 1904) | 
| First holder | Admiral Arthur Herbert (as Senior Naval Lord) Admiral of the Fleet Sir John Fisher (as First Sea Lord) | 
| Deputy | Deputy First Sea Lord (1917-1919, 1942-1946) Vice Chief of the Naval Staff (1941–1946) Deputy Chief of the Naval Staff | 
| Website | Official website | 
First Sea Lord, officially known as First Sea Lord and Chief of the Naval Staff (1SL/CNS), is the title of a statutory position in the British Armed Forces, held by an admiral or a general of the Royal Marines. As the highest-ranking officer to serve in the Royal Navy, the chief is the principal military advisor on matters pertaining to the navy and a deputy to the Secretary of State for Defence. In a separate capacity, the CNS is 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.