Abstract: This is the first survey of Unionism, the ideology of most of the rulers of the United Kingdom for the past 300 years. Because it was taken so much for granted, it has never been properly studied. In the twilight of Unionism, it is possible to see its long shadow over British and imperial history since 1707. The book studies the crucial time points at which the Union was built up and partly taken down: 1707, 1800, 1886, 1921, 1974, and 1997 to date. Primordial Unionism (the belief that the union is good in and for itself) now survives only in Northern Ireland. Instrumental Unionism supported the Union as a means to other ends, such as the Empire and the Welfare State; but the first is gone and the second is now evolving differently in the four territories of the UK. Representation and finance are the unsolved, and arguably insoluble problems of the post-1997 devolution settlement.

Keywords: unionism, Scotland, Wales, Ireland, Northern Ireland, Acts of Union, British Empire, parliamentary sovereignty, primordialism, instrumentalism, West Lothian Question, Barnett Formula