His pre-war occupation may provide a clue as to what he was doing. I have seen records of men who who clerks and who were enlisted in the army and spent their entire time in uniform working as clerks. Ditto platelayers [railway] and engineers. The army was a massive undertaking, it needed clerks, builders, railway engineers, transport staff, catering staff, etc., etc. There were a substantial number of men who were in uniform and never fired a shot in anger. Men who after wounding or sickness were re-classified as unfit for front line service were still of use to the army and were re-allocated to where their skills could be of use.
jds1949