Might be slightly O.T, however that spring might be a T front spring. The photo does show us something of the 'other' work of WW1 soldiers.
Caption- "Building up motor car springs in a 1st Divisional workshop. The state of the roads in this area caused frequent breakages to transport."
Instead of repairing damage I wonder if he isn't making overload springs to allow the civilian vehicles to better handle their new role in the military?
Judging by the boy warming his hands over the forge, it must be a chilly day.