For only the fourth time in its history the ultimate collectable for enthusiasts of the Glasgow Style is on the market with offers invited in excess of £3m.
When owner David Cairns bought the Grade A listed property 12 years ago it was in poor condition with its period features either removed or decorated over. It has been a labour of love to see the seven-bedroom house returned to its 1902 condition and style.
Mackintosh was commissioned to build Windyhill in 1900 for William Davidson, the merchant who became one of his lifelong supporters.
What really sets the property apart from Mackintosh's other commercial projects is Windyhill's adherence to the strong traditions of Scottish baronial architecture, including an L-shaped plan, harled (weatherproofed) exterior, unadorned window openings, steeply pitched slate roofs and chimneys at the gable ends.
The garden is over two acres and still true to Mackintosh's original design, including four distinct spaces and a lily pond into which the architect jumped when a fake beard he wore during Christmas high jinks caught fire.
Mackintosh and his wife, Margaret MacDonald, had complete control over the Windyhill project, designing the furniture, fireplaces, panelling, stained glass and light fixtures - a typical blend of strong right angles and floral-inspired decorative motifs. Pamela Robertson, senior curator at the Hunterian art gallery and museum in Glasgow, describes the house as "Mackintosh's first essay into the room as a work of art".
Mr Cairns - who would not have described himself as a collector of Scottish Arts and Crafts prior to the purchase of Windyhill - oversaw all of the renovation work with the input of the Glasgow School of Art and the Hunterian. Some of the original furnishings were traced in dramatic circumstances. The dining room and bedroom light fittings were retrieved via the Scotland Yard Antiques Recovery Department, while a raid by the NYPD on a house in New Jersey unearthed other original Windyhill lights. Leaded glass panels were returned to the house after they emerged at auction in Edinburgh.
Whenever original elements had not survived, these have been remade by approved craftsmen, while space was found for occasional 21st century 'essentials', including Bose surround sound and an Aga in the kitchen.
With the help of Euan Mundy, the Glasgow art dealer and advisor, Mr Cairns hung paintings by the Scottish Colourists and John Quinton Pringle - similar to the works collected by the first owner William Davidson - and decorated with Wemyss pottery.
Charlie Smith of London Real Estate Advisors, who are handling the sale in conjunction with Ballantynes, said: "Windyhill really is one of the most important 20th century houses to come to the market in recent years.
"The property is more than just a house. I wouldn't be surprised if it sold to an art collector, or an architectural enthusiast."
Interior and exterior views of C.R. Mackintosh's Windyhill, on the market for £3m.