Simon Winder is a publisher, but in another life he was probably a schoolmaster of that half-legendary species whom pupils have jostled each other to be taught by. However unostentatiously worn, his knowledge is vast, convincing you all the more through its leaven of dedicated enthusiasm. He is patient with the slowcoaches, offering them short cuts and simplifications without the least hint of condescension, and he has a good teacher’s love of corny jokes, unlikely coincidences and far-fetched analogies.

Lotharingia, by the same token, is like one of those lessons, punctuating even the dreariest and most disaster-laden of school days, in which we long for the bell not to ring. This book is the last part of a trilogy Winder began with his memorable Germania and continued with Danubia. In these books his historical and cultural trawl appears so comprehensive as to persuade us that anything left out probably wasn’t worth including in the first place. This final instalment is less regionally specific than its predecessors. In its title Winder invokes the name of a vanished Middle Frankish kingdom carved out in AD 843 for one of Emperor Charlemagne’s grandsons. Its frontiers, never too strictly defined, embraced what is now Belgium, Holland and Luxembourg, together with eastern France and Germany west of the Rhine.

Taking advantage, however, of this territorial vagueness, the work begins on a part of the continent now accessible only to deep-sea divers, that very same Doggerland that forms the background to Julia Blackburn’s recently published Time Song. Make what you will of the fact that Britain was an outlier of