Bar Locks and Early Church Security in the British Isles examines the evidence for the measures taken to make church buildings secure or defensible from their earliest times until the later medieval period. In particular it examines the phenomenon of 'bar locks' which the author identifies in many different contexts throughout England, Wales, Scotland and Ireland. Bar locks take various forms and can be made of different materials, but they all provide a means of locking a door by placing a bar behind it from the inside which is then secured onto the door frame or housings on adjacent walls. The most dramatic examples are provided by thick wooden bars slotted into recesses incorporated in the adjacent door jambs. The volume describes and lists all the examples identified by the author and also publishes his photographs of the evidence for the first time. The recognition of the role of bar locks in securing churches led the author to consider further measures which may have been introduced to enhance church security; these measures could Have had major implications for structural change and design in the buildings. These supplementary protective requirements and methods for achieving them are many and various and are also considered in the volume.

This work follows the study of the ecclesiastical geology of almost all Anglo-Saxon religious sites throughout England. There, it proved possible to both understand and distinguish clearly obvious patterns in the use of stonework, to determine the use and value of specific rock types, and to illustrate diagnostic features which could be used to identify building of that period. Subsequent studies of ecclesiastical sites, in Scotland and the Scottish Islands, the Isle of Man and Ireland expanded the value of the English studies by revealing closely analogous examples of the same indicative features. Beyond the domain of the Anglo-Saxons but of the same age, they were shown to follow a fashion; to this fashion the name 'Patterned' was applied.

In this study John Potter provides both an introduction to ecclesiastical geology in the British Isles, and then applies the methodology which he has outlined to the analysis of the stonework of a number of early churches in Ireland. In particular Potter highlights the use of vertically bedded stonework in pre-Romanesque churches, drawing parallels between English, Scottish and Irish examples.

This study takes a geological approach to the study of the flint walls of Great Yarmouth, generally considered to have been constructed when the town was at the height of its power and wealth in the fourteenth century. It shows that in fact the construction history is far more complex, with virtually the whole of the walls undergoing regular and extensive rebuilding and repairs.