For the first time in modern British history, pro-independence parties govern Wales, Scotland, and Northern Ireland simultaneously — a convergence that transforms what was once a scattered aspiration into a coordinated political force. In Cardiff this week, the leaders of Plaid Cymru, the SNP, and Sinn Féin signed a memorandum affirming each nation's right to seek independence and calling on Westminster to prepare for constitutional change. The moment raises a question that Prime Minister Andy Burnham has yet to answer with any clarity: what holds a union together when its parts begin, in conc