Hi Peggy,
The British Royal Air Force Airmen’s Service Records hold a lot of information on Arthur. He attested Toronto 22 Feb 1917 age 24 yrs 1 mth. Service number 70044. Address at that time 952 Denman St, Vancouver. Occupation Miscellaneous (Aviator Cadet). Previous military service 50th Gordon Highlanders 4 mths, 11th C.M.R. 4 mths.
Discharged 4 June 1917 selected for appointment to temporary commission to H.M Forces (RFC)
When I get to download matching images I’ll upload for you.
BTW, there is also an Airmen died in the Great War entry that lists he was a Lieutenant, Pilot, Killed whilst flying, in (aircraft) Camel E7137. (That was it’s reg number)