David Erskine, later 11th Earl of Buchan, was an antiquary and unsuccessful political reformer. Schooled by his parents, both of whom had studied mathematics under Colin Maclaurin, he later attended classes at St Andrews, Edinburgh and Glasgow. After his succession to the earldom in 1767 he returned from his military commission to improve the finances of the family estate. A keen patron of scholarship and the arts, Buchan founded the Society of Antiquaries of Scotland in 1780. As its somewhat overbearing leader he contributed both money and objects to the Society’s collections. Buchan’s odd social behaviour and unconventional political views earned him the reputation of an eccentric, but his collection of portraits became the founding collection of the Scottish National Portrait Gallery.