What is my nationality if I was born in England and have a British?
I, too, was born in England but emigrated to Canada many years ago. Since Canada does not require me to surrender British citizenship, I carried both a British passport and, once I became a Canadian citizen, a Canadian one as well. So long as Britain was a member of the EU, I could also take up residence in Europe with a minimum of fuss. Since Brexit, of course, that privilege no longer exists. Like me, you have dual citizenship in Canada and Great Britain. Its not something you apply for and nobody gives you a certificate, its just the way it works. Canadians are permitted to take foreign citizenship while keeping their Canadian citizenship.