This series consists in origin of official correspondence directed to the Secretary of the Admiralty for the information of the Lord Admiral or the Lords Commissioners. In time the series developed into a collection of correspondence to, from and within all departments of the Admiralty. Minutes were increasingly noted on the in-letters and from 1869 special minute sheets were added to important letters when they were received. Drafts and after 1869 copies of related out-letters were placed with the in-letters, and with the grouping together of all papers on a given subject the series became composed of files of the modern type.
In addition, the nature of the papers in this series changed: the centralised direction of naval affairs from 1832 resulted in the reference to the Admiralty Board, or individual members of it, of all matters involving policy decisions, and thus in the creation of papers in the Secretary's Department. As a result, by the 20th century, most papers that are now in ADM 1 related to internal Admiralty correspondence, memos and papers, and were less likely to be 'driven' by incoming letters to the Admiralty Secretariat.
The organisation of ADM 1 differs depending on the period and the series has been split into sub-series to reflect this [ADM 1 on the on-line catalogue is in the process of being re-organised to recognise these divisions].
From circa 1690 to 1839 (ADM 1/1-5494) the series is organised into groups according to the source of the incoming letters. For example, letters from the Commander-in-Chief, Baltic (whatever their subject) are grouped together in pieces 2 to 18; letters from the senior officers of other naval squadrons, stations and yards are similarly grouped. Letters from Captains and Lieutenants have also been placed together, as have letters from other government offices.
From 1840 to 1913 (ADM 1/5495-8364) the series is organised first into year groups, and then within each year into broadly the groups used in the pre 1840 arrangements. From 1869 these pieces often include internal papers, minutes and out-letters relating to the in-letter in question.
From 1914 to 1934 (ADM 1/8365-8779), the organisation into years continues, but the documents are arranged by an anomalous piece/item numbering scheme. This is explained in the more detail in the arrangement section of this sub-series.
From 1935 to 1938 (ADM 1/8780-9443), the item numbering system is no longer used but the organisation by year is retained. From this period onwards increasing numbers of earlier stray or late transfer documents have been included thus disrupting the year-by-year progression of the series established in 1840. In addition, the organisation of records within each year group also shifts towards either the ADM 12 code (or 'cut') indicating the subject of the papers in question, or by alphabetical order of their old Admiralty Secretariat references, that indicate the Admiralty department in which the file was created.
For the periods 1938 to 1945 (ADM 1/9444-19191) and 1946 to 1951 (ADM 1/19192-23058) these documents have been ordered by ADM 12 code in the catalogue, but as a result this has placed them out of piece number sequence. The piece number sequence is based on their former Admiralty Secretariat references year by year and can be discerned from viewing the packing lists in the paper catalogue at Kew. A significant number of strays and late transfers can be found in these sub-series.
After 1951 (ADM 1/23059-end), the arrangement by year is resumed and within each year by former Admiralty Secretariat reference. Numerous strays and late transfers are also to be found in this sub-series.