Hi Dominique
It would appear a Cdn soldier named Buckerfield also served in the First World War. He was from Birch Falls/Parry Sound, Ontario which is near the grave (Ullswater) and the Father (is that "E.W. Buckerfield" on the envelope?) who received the letter (Gravenhurst).
Ernest William Buckerfield was born in 1893. He was a Salesman when he enlisted, His Mother was Emily in Parry Sound. Served the War in the Canadian Army Service Corps being wounded, having Typhoid fever and Influenza as well as earning A Military Medal for Gallantry. London Gazette 31173-11-2-19
Maybe the Buckerfields and the one you seek were from that area?
Ernest's service file is freely available here:
http://www.bac-lac.gc.ca/eng/discove...IdNumber=73600
Your best bet is to request Edward Buckerfield's WW2 file from LAC. Without proof of death, it will be redacted for personal info but you may glean more info as to service.
regards
Darrell