PRN 64904 Westgate Mill had been the site of a corn mill continuously since the Middle Ages. Documents from the 1300s onwards speak of it as the 'Pond Mills' or 'Dam Mills': always in the plural, because it was actually a "double mill" with two separate wheels and two independent mechanisms. Corn milling continued at this site until the mid 18th century when the mill was converted to industrial use.{1} A hemp mill and bleaching house was established along the banks of the River Slea by Thomas Foster and John Foster in the mid 18th century. The mill was associated with ropemaking, the joint concern of the Foster and Hill families (see PRN 64905). In Hare's survey of 1783, we find Thomas Hill and John Foster occupying a Hemp Mill at the end of Westgate "consisting of one water wheel and proper works for beating flax" and a bleaching house of stone and brick near to it. The Hemp Mill which Foster and Hill used to beat their flax has now gone. It was the highest mill recorded on the River Slea and stood where Castle Causeway and Westgate join, close to Electric Station Road. Part of the mill race can still be seen running under the road, on the opposite side of West Banks footpath. Some brick footings are also visible, either from the mill or one of its outbuildings.{1} After Foster and Hill vacated it, several corn millers again occupied the Westgate Mill: the conversion from grinding to industrial use and back again was a simple one. The last recorded miller was John Tirner Almond, who went bankrupt in 1895. After him, the mill apparently fell into disuse.{1} The Domesday Survey mentions eleven mills on the Sleaford estate. A significant number had apparently disappeared by a comparatively early date. From the time of 1258 custumal, however, it is possible to trace the hsitory of the remaining five and locate their positions with considerable ease. The uppermost ('Pond', 'Dam' or 'Castle') mill was counted as a 'double mill' for much of its life. This may simply mean that there were two sets of millstones driven by one wheel; but the frequency with which it is given plural forms in medieval documents, and the explicit reference given to it as two mills 'under one roof' or 'in one house' in the sixteenth century, makes it more likely that there were originally two wheels in operation. It wa situated at the point where the Slea was crossed by the raised causeway leading to Sleaford Castle; but it seems originallt to have be approached along a road known as 'Millgate', which branched off one of the medieval routes from the nearby villages into the town.{2}