The National Archives holds the service records for most ratings who joined the Royal Navy between 1853 and 1923 in the Registers of Seamen's Services (held in the series ADM 188) and the Continuous Service engagement books (held in the series ADM 139). Service details are only recorded up to 1928.

Service from 1853 to 1872 (series ADM 139) 
Until the early nineteenth century the Royal Navy used impressment to man warships. However it created problems during times of war when there was an urgent need for more ratings to man the ships. From 1853, all boys from the ages of 14-17 joining the navy had to sign an engagement to serve 10 years, from the age of 18. There was the possibility of serving further engagements, towards the 20 years required for a long service pension. This form of service was also extended to those joining aged 18 and over.

Existing ratings could opt to serve an initial 7 year continuous engagement, along with further engagements to qualify for a pension. For each engagement served, a continuous service number was issued. These numbers are also known as "CS numbers". So it is possible that a rating could have been issued with several continuous service engagement numbers throughout his career.

CS numbers 1 - 40,000 were issued from 1853 - 1858
CS numbers 1A - 40,000A were issued from 1859 - 1866
CS numbers 1B - 40,000B were issued from 1867 - 1872
The covering dates relate to the opening of the registers.

Pieces 1- 220 of ADM 139 are currently available at DocumentsOnline, with the remainder being added in 2009.

Service from 1873 to 1923 (series ADM 188)
In the original documents there are three groups of service records covering the periods: 1873 - 1891; 1892 - 1907; 1908 - 1923.

If a rating joined the Royal Navy before 1873 and continued service after 1873, he might have a service record in both the ADM 139 and ADM 188 series. Also, some men may appear to have two accounts of service within ADM 188; firstly in the register and then continued in the Continuation Books ("new register"). These are linked together, so both are attached to the same man's entry.

The covering dates, 1873 - 1923, relate to the opening of the registers. Entries can continue for many years, according to the length of service of each seaman. While the last entrants were added in 1923, further entries were made to existing registers up until 1928. In 1928 the Royal Navy adopted an index card system instead. The number systems are slightly more complicated. From 1873 an "Official Number" was allocated to all Royal Navy ratings. The General Number (or "O" number) was used from 1873 to 1907.

From 1894 the number system for entrants became more specialised. Blocks of numbers were introduced for six different classes of ratings. By 1907 a similar numbering system was introduced with four different prefix letters to denote branches, or groups of branches. This revised scheme was used for new entrants from 1908 to 1925.

Bushby, Harold Cumpston Official Number: F31809 Place of Birth: Hull, Yorkshire  Date 22 November 1890 Catalogue reference ADM 188/623
Dept Records of the Admiralty, Naval Forces, Royal Marines, Coastguard, and related bodies
Series Admiralty: Royal Navy Registers of Seamen's Services Piece 31501-32000

Compston, William George Official Number: J79559 Place of Birth: Cinderhill, Staffordshire  29 January 1900 ADM 188/806

Will of Campston, George Rank/Rating: Midshipman Ship Name: Leviathan
Ship's Pay Book number: 1458 Date 18 January 1804 Catalogue reference ADM 48/19
Dept Records of the Admiralty, Naval Forces, Royal Marines, Coastguard, and related bodies
Series Navy Board, Navy Pay Office, and Admiralty, Accountant General's Department: Seamen's Wills Piece C

Medal listing of Compson, Edwin Walter Discharge number: R269322
Date 19 October 1925 Catalogue reference BT 395/1
Dept Records of the Board of Trade and of successor and related bodies
Series Registry of Shipping and Seamen: Database of World War II Medals issued to Merchant Seamen Piece Database of World War II medals issued to merchant seamen

Compson, George Ernest Official Number: M20970 Place of Birth: Walsall, Staffordshire
 08 September 1894 ADM 188/1059
 
Odell, Compson Official Number: K38044 Place of Birth: Southampton, Hampshire
 25 September 1891 ADM 188/943
 
Compson, Frederick Official Number: 213256 Place of Birth: Birmingham, Warwickshire
 19 February 1885 ADM 188/373

Compstone, Frederick Edward Official Number: 297896
Place of Birth: Liverpool, Lancashire Date 14 June 1875 Catalogue reference ADM 188/482
Dept Records of the Admiralty, Naval Forces, Royal Marines, Coastguard, and related bodies
Series Admiralty: Royal Navy Registers of Seamen's Services
Piece 297501-298000

Crumpton, James Henry Official Number: J81356 Place of Birth: Dudley, Staffordshire
 23 November 1899 ADM 188/809

Crumpton, Lloyd Official Number: F41849 Place of Birth: Walsall, Staffordshire
 13 November 1899 ADM 188/633
 
Crumpton, Henry Official Number: 182461 Place of Birth: Smallheath, Warwickshire
 22 May 1879 ADM 188/305

Cumpsty, Edward Official Number: 131611 Place of Birth: Liverpool Date 11 October 1859
Catalogue reference ADM 188/178

Dept Records of the Admiralty, Naval Forces, Royal Marines, Coastguard, and related bodies
Series Admiralty: Royal Navy Registers of Seamen's Services
Piece 131501 - 132000