The King's Mill was one of the earliest and most important buildings of its kind in the city. It had already been established by the time the Great Domesday Book was compiled, indicating an early medieval origin, and it was in continued use until 1800 when it was converted into a private residence. During the watching brief three structural elements, each relating to the medieval structure of the King's Mill. These were: brick lined slots running along the sides of the building, substantial timber piles cut into the area between these slots, and further downstream, a cross wall of worked Folkestone Stone. The results of the watching brief indicate that much evidence pertaining to the medieval mills still survives, fossilised within the standing remains.

The present standing walls are mostly that of the King's Bridge House, though there are fossilised portions of wall belonging to the medieval mills, in particular the external wall facing the Great Stour, which has much medieval fabric still visible. This includes the remains of a brick-lined roundel, which may have been the hole through which the axle of the western mill wheel passed. The brick lined slots ran inside and parallel to the main walls of the building and were indicated by narrow yellow and red bricks of 16th or early 17th century date. The position of the western slot in relation to the roundel suggests that it was cut to accommodate the corresponding trundle well of the mill. The mill had two wheels, however in many medieval documents they are usually mentioned in association with three grinding stones, it is not clear how two trundle wheels could drive three stones. The tops of five substantial timber piles, measuring c.30cm square were also exposed. They appear to be of a similar date to the brick walls, as they are built up against at least three of them. The mill was set above the level of the river on these piles. A slice of a pile was taken for dendrochronological analysis, however the wood was too knotty and had a very contortes ring pattern. The possible remains of the Folkestone Stone wharf around the mill were also observed (1).

<1> Canterbury Archaeological Trust, 1996, A Watching Brief undertaken at 24 The High Street, Canterbury (Unpublished document). SKE8313.