Mystery solved: George 's posting to the front explains his rank

 Here is a picture of Corporal George Critchley in his World War 1 uniform with a single corporal's stripe on the sleeve of his left arm. The badge on his cap is from the Prince of Wales Own Civil Service Regiment. A chance meeting of a friend and colleague today answered the question of how George came to serve most of WW1 in the capacity of a sergeant training Australian soldiers to use rifles. My friend is a retired lieutenant colonel and also retired Blue Badge tourist guide. I asked him if he knew why George had served most of the war in the capacity of a sergeant, but went to the front in Amiens in 1918 as a corporal. After I explained that George had joined the Prince of Wales Own Regiment as a corporal, spent years based in London as a sergeant, but was sent to front as a corporal, he said: "The same thing happened to me. I was promoted to Staff Sergeant, but when I was posted abroad my rank reverted to Sergeant. Promotions happen where there is a need, but when you are posted, you make the move in your former rank."

  Below is a picture of George with his Sergeant's stripes with an Australian School of Musketry cap badge.

 I already have remarked on the appalling loss of life at Amiens. George died on 9th August 1918, probably the victim of an explosion, although I haven't yet researched this. He wasn't reported "missing feared dead", there must have been witnesses, as his parents were informed he had been killed in action.