National Archives
 (formerly known as the Public Record Office),
Ruskin Avenue,
Kew,
Richmond,
 Surrey
TW9 4DU.

Records relating to soldiers who served after 1920 (other ranks) and 1922 (officers) are still held by

#The Ministry of Defence ,
Historic Disclosures,
 Mailpoint 400,
 Kentigern House,
65 Brown street,
Glasgow
G2 8EX
Website: Army Personnel Centre

You can find more detailed guidance for military on the Ancestor Tracing pages within this
Website: Army Museums Ogilby Trust

Address of all the Army museums can be found on this.
Website: www.armymuseums.org.uk

Commonwealth War Graves Commission
2 Marlow Road, Maidenhead
Berkshire SL6 7DX
Website: www.cwgc.org

National Army Museum
Royal Hospital Road, Chelsea
London SW3 4HT
Website:  www.national-army-museum.ac.uk

Find out all you can about them, eg Regiment, date of birth, rank anything speak to the family get them to remember. #You must be family to obtain records from some of them, they may ask for proof, some charge an administration fee.
Go to your nearest Army museum or call them. They sometimes have archivists that will help you and offer advice.

But last of all, don’t
GIVE UP ON THEM.
They need to be remembered.