[1] Chapter 1 starts from the observation that recent work on contact linguistics in well understood social contexts provides a new platform for trying to use evidence for historical language change as evidence for past social contexts and interactions.

Compared with other academic studies in historical linguistics, it is written in a usually plain and accessible style.

It argues that this contains features strikingly similar to Old Irish (particularly regarding the Old English vowel-changes known as 'i-umlaut' and 'breaking'), and that in these respects Old Irish may provide good evidence for the kind of Celtic spoken in south-eastern Roman Britain at the time of the Anglo-Saxon settlements.

Thus the chapter argues that the shift reflects Latin-speakers switching to German and carrying features of their own pronunciation over to it.

Schrijver's ideas, many of which appeared in the form of articles prior to the publication of the book,[2][3] have been the focus of fairly extensive academic discussion.