That's what Theresa May says, anyway.
PM Theresa May makes case for 'our precious Union' - BBC News
Ms May is misinformed.
What we are, Ms May, is two nations plus a principality and a province. Put that in your pipe and smoke it.
We are also three peoples. We are the English, the Scots and the Welsh. The proddy Ulstermen are belligerent rogues left over from Cromwell's genocidal plantation policy and the long-suffering papists are Irish, neither category being a British People.
The sooner the British Isles become three independent sovereign nations the better, unless anyone thinks Welsh independence would be a good move too.
I note in passing that, for the first time in my life, I do not know the marital status of the Prime Minister.