From National Archives site there are a couple of John Biddles in Artillery units but their Middle name initials are wrong. However there is this record:

Description Medal card of Biddle, John James
Corps Regiment No Rank
Machine Gun Corps 31822 Private

Date 1914-1920
Catalogue reference WO 372/2

If you saw the recent repeat of "My Family At War" on Yesterday, BBC's Kirsty Wark's great uncle was in the Machine Gun Corps, it was considered a suicide unit, so welldone for John James for surviving the War !
By the way Hilary, Ancestry records sometimes include the original handwritten Enlistment documents for individual soldiers, so well worth a look.