Neither of my English parents applied for Canadian citizenship until the 70’s, because the passport rules changed, I think. My father came here as a child, joined the Cdn army in 1939 and met my mother in Sussex, and they married there in 1945. They were just considered British subjects who lived in Canada. I believe those who came here from outside the UK must have had to do some paperwork, swear allegiance to the British monarch…interesting to know how that was managed.