If buildings, like people, have their seasons, then Flint House is definitely a winter house. The monolithic, wedge-shaped building is veiled in a quartz skin that graduates from glassy darkness at the base through lightening bands of grays to the chalky whites of the stepped roofline. Built in the hinterlands of Buckinghamshire’s 5,500-acre Waddesdon Manor estate, the house virtually dissolves on a cold-weather afternoon into misty skies and a sparse agricultural landscape.