Great story. Of course he would have been issued a Ross MkIII until the Ross was withdrawn in 1916. Since "Vimy" is carved on the stock, the work must have been done after that battle in April 1917. The rifle would have been impounded for refurbishment, not destruction. It might have been a rifle he salvaged from a casualty rather than his issue rifle. If it has no C Broad Arrow stamps that might be the case: a rifle from a Britishicon casualty. From the condition it's hard to believe that rifle was found on the battlefield after the war. More likely one of his comrades saved it, or perhaps at some point while at Enfield a new barreled action was fitted to the stock.

Amazing story anyway, thanks.