Mack,
I see the Official History / Record showing gazette entries on 3/6/18 & 21/10/18. James was absorbed in 17th when the whole of 19th Bttn was disbanded on 6/2/18. It's possible the award relates to repeated work at St Quentin in March 1918, but may also be the previous work recognised by Haigh the previous autumn - or both.
CSM J E Young was awarded DCM with the same Gazette date entries. His DCM MIC confirms 17th Bttn, providing a little more support to the Official History.
The DCM certainly does NOT relate to the 1st Bttn Border Rgmnt.
For the moment I'll assume the 17th Bttn, although I'm a bit surprised to see only 3 DCMs for the men of 19th Bttn, compared with 11 for 16th, almost 20 for the 17th & 11 for 18th. The difference may be explained by the incorrect allocation to the recipients' Bttn on the date of Gazette.
James has a full service history, but nothing more associated with the DCM than I've picked up. Apparent posting in 2nd, 3rd, 11th, 14th, 17th, 19th Manchesters and 1st Borders is quite a list - some are very temporary.
T