From a technical perspective, any wooden chair whose legs, back and arms (if existent) emanate from a solid seat is a Windsor chair.
Here then is a pair of fruitwood Windsor chairs that are coming up for auction in Christie’s The English Collector: English Furniture, Clocks, European Ceramics & Portrait Miniatures in King Street, London on the 19th of May 2016.
Lot 74; a pair of George II fruitwood open armchairs, circa 1740, estimate £20,000 – £30,000. (Christie’s)
These solidly constructed ‘Hartwell chairs’ crop up periodically (see Christie’s Lot Notes) and normally attract high prices.
I blogged about a comparable Windsor chair in the Victoria & Albert Museum.