I totally agree with Ronda but, taking a closer look, my opinion is, these men were not front-line soldiers. Most of them look too old, perhaps they were in the Labour Corps? They should have been wearing cap badges, could it be the picture was taken at an angle that just excludes the badges? They would have been on the men's left side of the cap.
The criteria required to be in the Labour Corps was, men who weren't fit enough to carry a full pack 5? miles or, deaf in one ear, blind in one eye or have very poor sight. Some of these men do not look fit or able-bodied.
Taking a closer look, I do think they are wearing cap-badges.