The first light railway worked by the British was also a French one. It had a track gauge of 60cm (2 feet), and this was applied to all light railways constructed by the British. The British system developed tracks that were prefabricated in lengths, that were in themselves very lightweight. They could be carried easily, and laid quickly. For lengths of rail that were more permanent, they were laid like full-size tracks, with sleepers and stone ballast.

The Light Railway Companies came into existence when it became clear that the maintenance of roads was becoming a severe problem; in February 1916 the first new railways were sanctioned. Of course, by this time the warfare on the Western Front had become one of fairly static trench lines. It made sense to feed them using fairly static transport systems.

The Light Railway Operating Company consisted of approximately 200 men, in a number of trades: Drivers, Brakesmen, Guards, Wagon Repairers, Repair Shop Engineers, Traffic controllers, and Storesmen. There were few officers among this number (for example, the 31st LROC was commanded by a Captain). The job of the type of Company was to run the trains, with the tracks being laid by RE Railway Engineers - often with the assistance of whatever Labour Corps Company or ‘resting’ infantry were at hand.

Moved to Maroeuil (on the River Scarpe, and a railway line) north-west of Arras, and built a Company HQ and camp there that remained until March 1918. Used an old cotton mill as base. On first arrival they took over about six of the standard workhorses of the light railways, the 20hp Simplex petrol locomotive.

Took over the operations of all light railways in the Arras area, supplying the front-lien and artillery units of Third Army. The main lines appear to have been the ones running out of Arras to the east, along the Scarpe valley towards the front-line positions of Fampoux.
The main pick-up point for goods to be carried was called “Q Dump”. From there, ammunition, trench supplies, timber, men and a myriad other supplies would be carried forward. Men, wounded, and salvage were the main cargoes for return journeys.

The men of the LROC enjoyed a considerable amount of individual freedom – quite necessary as they were charged with moving trains to and fro, getting them re-railed and repaired when accidents or break-downs occurred, etc. The officers and NCOs of the Company appear to have had a sensible attitude, that as long as men were back at camp when they should be, all was well. A simple recreation was going to the YMCA hut in nearby Etrun for a cup of tea.

The 31st worked the lines in front of Arras (including during the Battle of Arras in April 1917, when British artillery finally overcame its former supply difficulties and overwhelmed the enemy) until forced to move back in March and April 1918, when the enemy attacked in great force. The Third Army front was pushed back some way, but held. By May 1918, the 31st HQ was at Fosseux, a few miles further west of Arras, with the locomotives at Bernville. Much track had been lost to the enemy, and much more damaged, so the immediate task was to restore operating efficiency.

In August 1918, an Allied offensive opened that was to win the war. For the 31st, it meant many weeks of gradually extending the lines to keep up with the advancing armies, and all the time moving their centre of operations forward. The distance to be covered kept extending, as the attacking infantry moved much faster than the supply centres could move up. They moved first to the east of Arras, then further on to Bapaume, then Bourlon near Cambrai.