I'm English and my family and ancestry is entirely English to the extent of my knowledge. Down one of the many lines on my mother's side, there is some gypsy background. But whether they were Romanian or Irish or just English or anything else in descent is unknown.
As an English family we were obviously part of the British Empire.
I don't know of any long lost relatives or predecessors of mine who were part of the British Empire out in different areas of the world.
Some relatives of mine were Merchant sailors, but as far as I know the furthest they ever travelled from England was likely to be Ireland and/or France, but they mostly kept to England.
There's probably some chance that I've got some sort of relative who travelled to the Americas, or likely some who went to Australia and New Zealand (Most likely as convicts than well-to-do's I'd imagine).
So, as far as my ancestry goes, it is very likely that my family has forever lived in the British Isles. Possibility of descent from Celts, but equally a chance of descent from Normans. My Family name and all known previous Family names happen to be names belonging to commoners. Nothing lordly or regal. But that doesn't mean there's no chance of Norman descent, just that they would have been Norman commoners.
And then travelling beyond that, who knows. It's all Dark Ages at that point and there would be no way of knowing.