Glasgow School usually refers to the circle of artists and designers around Mackintosh in Glasgow from the mid 1890s to about 1910. Most notable were the Macdonald sisters and Herbert MacNair and with Mackintosh they were known as The Four. They made a distinctive and highly influential contribution to international Art Nouveau and are sometimes referred to as the Spook School. The Glasgow Boys introduced forms of Impressionism to Scotland in the 1880s and 1890s, developing their own individual interpretations of it, often highly coloured. As well as painting in Glasgow and its environs they sought scenes of rural life and character in other parts of Scotland. Principal members of the group included Joseph Crawhall, Sir James Guthrie, George Henry, EA Hornel, Sir John Lavery and EA Walton.