This book has been gestated for nearly a decade. Its origins lie in a study of the estates of the fenland abbeys of Thorney and Crowland. The effect of mortmain legislation on their endowments at a controversial period in the medieval economy proved more compelling than any other aspect of their chequered history of acquisition. Surprisingly, despite some invaluable pioneering works, it appeared that no one had written exhaustively upon the social significance of mortmain controls, although their operation had often been observed en passant, My first step towards a remedy for this omission was published in Past and Present in 1974. This preliminary article, ‘Mortmain in Medieval England’, served to show that the workings of mortmain law over a long period of time were both more complex and less predictable than had hitherto been assumed and that a full assessment would be of value to both political and economic historians.

The first chapter of the book deals with the enactment of the 1279 legislation and the circumstances which brought it into being. Such a survey must preface any investigation of the law in action, but since it is the aspect of mortmain legislation which has already received more attention than most, some of it very recent, my prime purpose here has been to coordinate the fruits of these researches and restrict my own contributions to the few remaining gaps.