After three hundred years, the Anglo-Scottish Union is in serious difficulty. This is not because of a profound cultural divide between England and Scotland but because recent decades have seen the rebuilding of Scotland as a political community while the ideology and practices of the old unionism have atrophied. Yet while Britishness is in decline, it has not been replaced by a dominant ideology of Scottish independence. Rather Scots are looking to renegotiate union to find a new place in the Isles, in Europe, and in the world. There are few legal, constitutional or political obstacles to Scottish independence, but an independent Scotland would need to forge a new social and economic project as a small nation in the global market-place, and there has been little serious thinking about the implications of this. Short of independence, there is a range of constitutional options for renegotiating the Union to allow more Scottish self-government on the lines that public opinion seems to favour. The limits are posed not by constitutional principles but by the unwillingness of English opinion to abandon their unitary conception of the state. The end of the United Kingdom may be provoked, not by Scottish nationalism, but by English unionism.