The sums are eye-watering. In 991 the English king Æthelred paid the Vikings £10,000 to stop them sacking the east coast of England. Three years later a sum variously recorded as £16,000 or £22,000 was given. In 1002 they were back: this time they got £34,000. No one could say that Æthelred didn’t try bribery first.

But what then? The answer, it seems, was butchery. On St Brice’s Day, 13 November 1002, the Anglo-Saxon Chronicle says Æthelred ‘ordered all the Danish men who were in England to be slain’. His motive? ‘The king had been informed that they would treacherously deprive him, and then all his councillors, of life, and possess this kingdom afterwards’, as the chronicle notes. ‘Without any opposition’, one version adds, although Æthelred’s reputation for indolence suggests his capacity to oppose anything was limited.

Who precisely was targeted? Probably settlers. A charter of 1004 refers to those attacked as ‘the Danes who had sprung up in this island, sprouting like cockle [weeds] among the wheat’. Mass graves have been found in Oxford and Dorset.

However many died, the massacre did not work. The Vikings returned in greater force; in 1007 Æthelred had to pay them £36,000. Within months of his death in 1016 they seized England itself.