I think the Protestant threat then is important to note, along with the very real Protestant threat of terrorism at the time of partition, which led Britain to ignore the Ireland-wide referendum for independence. If Scotland goes in September it will be even more difficult for Unionists to keep the British interested in the six counties. And I’m not sure we will even be using the term British then, since it was created to have a term to refer to the people of a united England and Scotland. Wales, the descendents of which are the actual Britons more than any other, didn’t seem to count because at the time it was joined to England modern ideas about repressing rebellion and separatism hadn’t come in yet.
I think by joining the EU many countries gave up much of the independence we associate with “nations” today. I don’t think Scotland’s “independence” will mean much when you look at a country like Canada; it still features the English monarch on its money, maintains an official residence and some kind of governor, yet some still consider it an independent country.
I though “British” was simply a reference to those on the island of Britain, or had their roots there; Catholics in Ireland (north or republic) never viewed themselves as British, while Protestants shipped over to lay claim to the Catholic land may well have considered themselves as such (since their roots were “British”).
I don;t believe Wales had enough of a sense of nation when it was absorbed by the larger population of the island of Britain centuries ago; while they have their own language and customs, I don’t think there was an ancient nation to which they can harken back today.