Many of the characters in this book have names that can be spelt in a variety of different ways. Swein Estrithson, for example, appears elsewhere as Svein, Sven, Swegn and Swegen, with his surname spelt Estrithson or Estrithsson. There was, of course, no such thing as standard spelling in the eleventh century, so to some extent the modern historian can pick and choose. I have, however, tried to be consistent in my choices and have not attempted to alter them according to nationality: there seemed little sense in having a Gunhilda in England and a Gunnhildr in Denmark. For this reason, I’ve chosen to refer to the celebrated king of Norway as Harold Hardrada rather than the more commonplace Harald, so his first name is the same as that of his English opponent, Harold Godwineson. Contemporaries, after all, considered them to have the same name: the author of the Life of King Edward, writing very soon after 1066, calls them ‘namesake kings’.
When it comes to toponymic surnames I have been rather less consistent. Most of the time I have used ‘of’, as in Roger of Montgomery and William of Jumièges, but occasionally I have felt bound by convention to stick with the French ‘de’. Try as I might, I could not happily write about William of Warenne in this book, any more than I could have referred to Simon of Montfort in its predecessor.