Each record is a transcript typically giving the following information. Note that earlier lists published in 1915 generally give more narrative than those published in later years. The amount of information listed varies, but the records usually include the following information about your ancestor:
Detail about casualty (eg wounded, missing, wounded & missing etc)
Between 1915 and 1918 The British Red Cross & Order of St John published regular lists of men missing in action during the First World War, about whom enquiries had been made. These lists were published at regular intervals, each list cancelling all lists previous to it.
Typical information includes a man’s name, regiment, battalion and company (for infantry battalions). Ranks are rarely given, but details about the date of casualty, the place where this occurred, and sometimes extensive additional information are included.
There are over 158,000 records in this collection which is published in partnership with the Naval & Military Press. The vast majority of these men will have complementary records already published on Findmypast in our medal index card, service and pension records, and prisoner of war collections.
Early lists published at the start of the war give detailed information for some men. For instance, 6745 John Cardwell of A Company, 2nd Gordon Highlanders appears in a list published in June 1915. Against his name it reads, “End of March  comrade called on wife bringing his watch and saying he had been killed. Received letter from colonel dated April 14 saying husband was wounded on March 11 [and] is in hospital. So far the news concerning him is quite favourable. Since then no news at all. War Office reports no casualty.”
Sadly, as it would later transpire, John had indeed been killed in action on the 11th March 1915. He has no known grave and is commemorated on the Le Touret Memorial in France.
Start with name and regiment and expand search terns as necessary. Always use the wild card asterisk * search to maximise your chances of success. For example, instead of typing “Argyll & Sutherland Highlanders” in the regiment field, simply type Arg