Vctenderness,
My father-in-law’s bio:
He was from Stroud, across the Medway from Rochester. Joined the RAF in 1941 and got his wings in the UK flying Tiger Moths. February 1942 has him in Canada being trained on the Anson in Carberry, Manitoba. He spent from June 1942 until February 1944 flying the Anson out of Hamilton Ontario’s Mt. Hope airport at Number 33 Air Navigation School. While at Mt. Hope he met the woman who would become my mother-in-law, a Canadian girl who became a sort of reverse war bride. He was shipped back to the UK in June 1944, transitioned onto “the heavies” (as he always called them), finishing the war on Lancasters. His reverse war bride joined him in the UK in late 1945 and he decided to emigrate to Canada in 1948.
We have all his paperwork (logbooks, paybooks, service and release books, etc) all in one bundle and there is no Canadian passport. I also remember him talking about getting his Canadian citizenship in ~1951, which of course would have been unnecessary had he have already been a Canadian passport holder and hence a Canadian citizen, as your father was.
Did your father have a Canadian relative and he perhaps decided to apply for Canadian citizenship and a passport on a whim? There were tens of thousands of British and Commonwealth nationals (we even let a few Americans in!) during the heyday of the BCATP and I’ve never heard of them being issued with Canadian passports.