G. G. Astill: A medieval industrial complex and its landscape: the metalworking watermills and workshops of Bordesley Abbey (CBA Research Report 92). London 1993.
During the years from 1980 until 1991, the east area of the former Cistercian Bordesley Abbey (Worcestershire) was archeologically researched. As a result England's and probably Europe's earliest proof for the use of water power in the iron factoring was found. A water wheel drove a hammer and the bellows of two smithies' fire places. It is supposed that the shaft transmitted the power directly without a gear unit, because there was nothing like that found (pp 269-271, p 282; reconstruction illustration p 270). The building, a wooden post construction, included the smithy itself and the water wheel house (reconstruction illustration p 262).
This first water powered factory is dated by dendrochronology into the time 1174-6 (pp 242-243, with a table of the whole result). It was in use until the late 14th century. Only some little changes have been there in that stage. The time came when mud filled more and more the drawing-off ditch. At first the manager made the pond higher. But floods deposited more mud and also the economic importance of the construction decreased. That made the abbey close the water propulsion (p 303).
The foundation time of the hammer dates long before the oldest written source about a metalworking watermill in England. This source tells about an oliver in Warley (Yorkshire) in 1349 (p 302, see also R. Holt: The Mills of Medieval England, Oxford 1988, p 150). A hammer that forged blooms is supposed in the first half of the 14th century in Chingley (Kent) (Holt, p 150).
The Bordesley hammer is founded in the time of the earliest written sources about the diversification of the water power technology. There are mentioned four fulling mills (Holt, p 153): Kirkby-on-Bain (Lincolnshire), probably in 1154; Heycroft nearby Malmesburg (Wiltshire), probably in 1174; Newham (Yorkshire) and Barton-on-Windrush (Gloucestershire) in 1185 (both were properties of the Temple Order).