The collaboration of Richardson and Sayles in the investigation of early English parliamentary history has long been justly celebrated. A full generation has passed since the publication of the first of those studies of theirs which have done so much to widen and deepen knowledge about medieval parliaments and have made their names, usually coupled, household words with students of medieval English constitutional history. The authors were influenced, no doubt, by some earlier historians, and the statement that they built on foundations laid by Maitland and McIlwain is not incorrect. In the volume, however, which is here under special consideration, The Governance of Mediaeval England from the Conquest to Magna Carta, they do not undertake, qua historians as distinguished from historical critics, to come this side of the reign of King John, when parliaments had not as yet assumed their later form and functions.IWhy, it seems not inappropriate to ask, was this latest joint product of their historical activities written; to what class or classes of readers was it particularly addressed? It was evidently not designed as a manual of the type that students of English constitutional history have long been familiar with; for one thing, its chronological scope is limited to about two centuries, from c. 1000 to 1215; and much of the book would be unintelligible to beginning students of the subject. An apologia, which serves as a Preface, and a preliminary chapter suggest answers to the questions that have just been asked.