Hi Mack,
This man's Service Record confirms he was captured at Trones Wood. Strangely, the Official Record omits Albert from the DCM list, but the citation confirms the number as 17/8361 and his Record identifies Montauban as the relevant place.
Gazetted 28/3/18 "for Montauban action" [1/7/16]. For conspicuous gallantry and devotion to duty. During a heavy bombardment a trench was blown in in several places and several men were buried. He at once started to dig them out under a very heavy fire, and rescued two men single-handed. He behaved in a most cool and courageous manner throughout the bombardment. *Albert was a resident of 69 Hilton Street, Higher Broughton. He had initially bean rejected as too small (5 ft 6 1/2") by the Navy. Aged 19 years and 9 months Albert was a former Cutter who enlisted 3/9/14. He trained with I Platoon, A Company holding a chequered record of discipline (42 Days C.B.) Listed as Missing, then PoW 11/7/16, Trones Wood. Notified to father, George on 17/8/16. Held in Dulman Camp to be repatriated at Leith on 10/12/18. He was domobilised on 12/3/19.