Ballast for Broad Gauge being hurried up the light railway as it is to be cut in a day or so.
The following additional information is from Martin Farebrother:
As already mentioned, the LR across the Somme at Frise, and part of that along the north side of the Somme, are not shown on later maps (Jan & Feb 1918). They were no longer needed once the SG line on the north side of the Somme had been constructed.