The united kingdom

As the referendum on Scottish independence approaches, it's worth noting that for all of the nationalism north and south of the River Tweed, Scotland and England really have become a united kingdom that would be painful to disentangle:

• Millions of English have at least some Scottish ancestry.
• Most of the Protestants in Northern Ireland have Scottish roots.
• The queen is the daughter of a Scottish mother.
• The current prime minister is the son of a Scottish father.
• The prior two prime ministers were Scots.