I'd prefer white ground red cross of St George. Top left quarter welsh dragon, bottom right corner red hand of ulster. Sorted.
Keeping the St Patricks Cross when only a small part of the island of Ireland is part of new UK ?the NU-K? is a bit presumptious.
and what will we call it, the United Kingdom of Britain and Northern Ireland?The United Kingdom of England, Wales and Northern Ireland?
Also if the perfidious ones go independent like they could opt to keep the constitutional monarchy and Betty could still be Queen in theory yes?