To this day, the United Kingdom is famously known for it's ethnic divisions, as the Irish, Scots, English, Welsh, and now the Cornish all harbor stereotyped hatred for each other, yet remain a united nation out of tradition and maintaining the status quo.
However, is there a way to make the English, Welsh, and Cornish consider themselves a single national entity? What POD is need after the personal union between England and Scottish crowns for this to occur?
Bonus points for integrating the Scots and Irish