ShaunJ posted this link on another post
https://www.apply-deceased-military-record.service.gov.uk/
To use this link for an Army enquiry (person born 1907 and since 1907) you will need to provide some brief military related Information about their Service, including proof of Death (P of D upload essential).
In their acknowledgement they have further requested his Date of Birth
or his Service Number. Supplied D of B.
Added:
We will try and let you know if they find the record of my late relative a Private, who left the Duke of Cornwall's Light Infantry at Bodmin, Cornwall in 1936, according to a DCLI letter we have (which provided quite a bit of the information required to complete the online Form questions).
2nd Add.
We have emailed photographs of the full DCLI letter and a later War Medal box (WW2) and explained that he worked in a Coventry factory during WW2 and assisted in recovery of Casualties on the infamous 1940 Blitz night. The box includes his name, address and a reference number on the outside and sent from Infantry Barracks, Exeter, Devon.
3rd Add
1936 DCLI letter has no Service Number, but confirms 6 & 1/2 years service.