There is an excellent - free - resource of Army Lists at Archive.org.
(There are also Army Lists on Google Books and a series (the same at on archive.org - but in a different display) at the National Library of Scotland (http://digital.nls.uk/british-military-lists/pageturner.cfm?id=88735803))
I have listed the archive.org First World War Army Lists at
I have a longer list running through the 19th and 20th Century at
The First World Army Lists are the Quarterly volumes. There were also monthly volumes which had slightly different information in them (see below).
The Army Lists ran to different numbers of volumes with up to three volumes as the number of officers increased as the war progressed.
The smaller writing under 'With an Index' gives important information about the different types of Army List and what they contain.
- Details regarding the Staff, Regimental Lists, Reserve of Officers ... are published in the Monthly Army List
- The latter two (ie Orders of Knighthood and Foreign Orders) in the January, April, July and October issues only of that publication.
- The War Services of Officers are published in the January issue only of this Army List.
The whole volume has 1989 pages and a detailed index which looks like
At the top it states 'References to the Graduation Lists are in Heavy Type'
Taking a surname at random, the references to Clayton are:
Notice that index numbers go further than the total page numbers. This is because within some of the lists there are several columns per page and each column is referenced in the index, or some pages have more than one page number.
The following screen shows the standard archive.org screen setup.
This volume is at: https://archive.org/details/armylistapr1914grea
Click the page expansion button (bottom right, next to the back or left arrow) and the following style of screen appears.
The pages can be found either through placing the cursor on the pages on the left (or right) hand side which indicates the page number, or by moving the hand at the bottom along the line.
However, a warning. As noted above the numbers in the index are not the page numbers, so there is an amount of narrowing down the page numbers until the correct one is found.
Alternatively, use the search box 'Search inside' to search for the names - the instances are shown on the 'hand bar' below. Searching of 'Clayton' will give all instances of the word.
The first on the list is Clayton AB which gives - once the correct index reference is found - the following half page
The top heading shows that he is a Lieutenant and then the columns give the relevant information, including Date of Birth and First Appointment. The crossed swords by his surname shows that he has seen previous action.
The second page shows the Army Veterinary Department.
Above the unit title is the wording Non-Effective Officers. This indicates officers who have retired from service
The Army Lists also include a large section called 'Forces of the Oversea Dominions and Colonies'
Note that the page numbers in this section have the number, and then pages number a), b), c) and d).
Another section is the is Warrant Officers in Receipt of Pensions, with helpfully the date when the pension was first received.
There are of course many other sections, but this gives a flavour of the sections within the Army Lists.
And finally ... there is one aspect that needs explanation - abbreviations, of which I have written a separate blog.