The photo looks as though it was taken early in his service - cap very stiff, and collar tailored [privately, for smartness]. Once in the field the cap would lost its stiffener, and the tunic would not look so pressed!
I do not know about chinstraps [I think brow bands are on horses!] and shininess.
Are you sure you have the right medal index card for Hugh? Usually a transfer will show up on the card.
Did he survive the war?
Depending on where he lived, he may be listed, with details of his unit, on the Absent Voters List at his home town. Some survive, other, as in Liverpool, do not. The survivors may be at a local authority office or main library.