FOUR Nations -- A History of the United Kingdom by Frank Welsh is the first single-volume history of the making of Great Britain and its subsequent disintegration. Massive and meticulously researched it is essential to understanding the current devolution controversies.

By comparison with the United States, the history of the United Kingdom as an undivided entity has been quite short. This book describes the history of each constituent part, their interaction, and the effect of external events. As soon as British history is seen as an integral part of world history, the perspective alters drastically.

Until 1803, France was optimistically assumed to be part of the realm. Less than a century elapsed between 1829, when the oath of allegiance was altered to allow Daniel O'Connell to take his seat in Parliament -- misnamed "Catholic Emancipation" which made the inclusion of Ireland rather more than a political fiction, to 1922, when the Irish Free State emerged.

Scotland, with England the main constituent of the UK since 1707, has retained its own legal system, administration and established church (the Queen changes her religion each time she passes Berwick). Wales retains a distinctive culture and language, albeit one on an expensive life-support machine.

Many cherished myths are exposed, many sacred cows are slaughtered and many shady corners are illuminated. From Agricola to Donald Dewar and Gerry Adams, the historical process is recreated. (Published by HarperCollins at £25).