British isles
is a geographical description that the Southern Irish hate. In fact I suspect they hate the Southern description too.

The UK is the Union of Great Britain and Northern Ireland. Hence Unionist politics.

And how come we omit Cornwall from this union/great bit. It is as much a principality as Wales, and could have elected it's own parliament long before devolution. The only barrier was expense and maybe the major owner - Prince Charlie. Who confusingly is the Prince of............