A corn mill dating from 1862 and powered by water turbines, Cilcewydd Mill was part of the industrialised model farm of the Leighton Estate (nprn 85833) owned by John Naylor, a Liverpool banker. The mill was built in two phases: the main block in 1862 and the second in 1868, in an identical style. In the 1930s it became a creamery (nprn 300111) and is currently a vehicle bodywork repair shop.
The mill is built of brick with stone dressings and now has a flat roof, although it was originally pitched, set behind a brick parapet; it is five storeys high, comprising the earlier north-south block of six bays, and the later lower rear wing, also of six bays with slate roofs. An office (nprn 85840) and storehouse (nprn 85841) are associated with the site.
Internally the ground floor is of concrete with access traps to the two late-nineteenth century MacAdam turbines (nprn 85839) below; these horizontally-set turbines, made in Belfast, are said to have bearings floating in mercury and may be the only surviving examples of the 'improved' MacAdam type. A headrace (nprn 85835), sluice (nprn 85871) and sluice bridge (nprn 85838), and tailrace (nprn 85870) are associated with water supply to the turbines. The upper floors are connected by fireproof spiral stairs which are the only original mill fittings to survive.
RCAHMW, 11 February 2009.