Susan Oosthuizen's fascinating research into the landscape history of the Bourn Valley, just west of Cambridge, is published as the first volume in a new series of mid-length (40K-60K words) monographs on fresh and unusual subjects within local and regional history. The series is published under the auspices of the Centre for English Local History, University of Leicester and the Centre for Regional and Local History, University of Hertfordshire, and marks the beginning of a welcome collaboration. Most historians and many archaeologists have seen a complete break, at least in physical terms, between the field systems of Roman Britain and the common or open fields of medieval England. If it is possible to unravel the relationships between pre-open field and open field boundaries in the Bourn Valley between about 600 and 1100 AD, then a significant step forward might be taken in our understanding of the origins of medieval open field systems in general. We might begin to understand the processes through which the fields, woods and pastures that had developed over the prehistoric millennia and the Roman centuries were organised into a completely new landscape: that of the medieval open fields. Field work has uncovered preserved prehistoric field patterns in the medieval furlongs of the valley. The unexpected discovery of what appears to be an 8th Century or 9th Century proto-open field pattern enables the author to outline a new model for the introduction of common fields in England. It is illustrated throughout with maps and photos.