James's reign marked one of the very rare major breaks in England's monarchy. Already James VI of Scotland and a highly experienced ruler who had established his authority over the Scottish Kirk, he marched south on Elizabeth I's death to become James I of England and Ireland, uniting the British Isles for the first time and founding the Stuart dynasty which would, with several lurches, reign for over a century. Indeed his descendant still occupies the throne.

A complex, curious man and great survivor, James drastically changed court life in London and presided over such major projects as the Authorized Version of the Bible and the establishment of English settlements in Virginia, Massachusetts, Gujarat and the Caribbean. Although he failed to unite England and Scotland, he insisted that ambassadors acknowledge him as King of Great Britain and that vessels from both countries display a version of the current Union Flag.

He was often accused of being too informal and insufficiently regal - but when his son, Charles I, decided to redress these criticisms in his own reign he was destroyed. How much of the roots of this disaster were to be found in James's reign is one of the many problems dramatized in Thomas Cogswell's brilliant and highly entertaining new book.