The smock mill is a type of windmill that consists of a sloping, horizontally weatherboarded or thatched tower, usually with six or eight sides. It is topped with a roof or cap that rotates to bring the sails into the wind. This type of windmill got its name from its resemblance to smocks worn by farmers in an earlier period.
Smock mills differ from tower mills, which are usually cylindrical rather than hexagonal or octagonal, and built from brick or stone masonry instead of timber. The majority of smock mills are octagonal in plan, with a lesser number hexagonal in plan, such as Killick's Mill, Meopham. A very small number of smock mills were decagonal or dodecagonal in plan, an example of the latter being at Wicken, Cambridgeshire.
Smock mills exist in Europe and particularly in England, where they were common, particularly in the county of Kent, where the tallest surviving smock mill in the United Kingdom, Union Mill, can be found at Cranbrook. They reached their heyday in the earlier part of the 19th century, after which the advent of steam power started the decline of the windmill.
Designed by the civil engineer John Smeaton, Chimney Mill in Spital Tongues, Newcastle upon Tyne was the first five-sailed smock mill in Britain. It was built in 1782 and is the only surviving smock mill in the North East region. However, the sails and original cap are no longer in place.
The oldest surviving smock mill in England (dated to 1650) is located in Lacey Green, Buckinghamshire. The hexagonal mill has been restored by the Chiltern Society.