This title may at first sight provoke a certain amusement. Some readers may be moved to ask: ‘The Anglo-Scottish Union a success? It produced four Scottish invasions of England in eleven years, didn't it?’ Many people, including myself, have written on the weaknesses and the difficulties of the Anglo-Scottish Union. Those weaknesses patently existed, and were significant. Yet most of the writing on the weakness of the Union has been directed to the task of explaining either the Covenanting Revolution, or the English Civil War, or both. It has therefore had a teleological bias towards concentrating on the weakness of the Union. Yet there is another trend, equally valid if equally teleological, which leads, not towards 1643, but towards 1707. It is necessary to survey the Union of the Crowns from both vantage points before we can get a fix on it, and approach the task of seeing it as it was.

This essay is not intended to unsay what I have already written on the weakness of the Union of the Crowns. It is intended to provide a context in which, in a perfect world, I should have put it in the first place. Neither then nor now has the Union of England and Scotland been free of strains, yet it has one solid achievement to its credit.