This series consists of Admiralty out-letter books containing orders to sea officers, instructions to sea and naval officers on the performance of their duties, commissions and warrants appointing sea and naval officers, and other out-letters. The majority fall into two sub-series, 'Lords' letters' and routine correspondence.
'Lords' letters' were the most formal. Depending on the date they were signed by the Lord High Admiral, by three or more lords commissioners of the Admiralty, or by the sovereign in person executing the office of Lord High Admiral. From 1689 two series of Lords' letters were kept, one, written in a personal form, confined to correspondence with the Navy Board, the Master-General of the Ordnance, and the secretaries of states (the last bound separately from 1695). Other orders and instructions signed as Lords' letters, including all Admiralty commissions and warrants were written in an impersonal style and signed both by the three lords commissioners and by the Secretary of the Admiralty 'by their lordships' command'.
The second series contains all routine correspondence not requiring the signature of the Lord High Admiral or members of the Admiralty Board, which were written and signed by the Secretary alone. These letters were first maintained as a distinct series by the Admiralty Board of 1679-1684 and again from 1689.
Most volumes of both series are indexed internally.