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.