William Arthur Jobson Archbold, Dictionary of National Biography… (1892)
“ His father purchased Dunnottar, Kincardineshire, from the last Earl Marischal in 1766, and his grandfather, Alexander Keith, an Edinburgh writer to the signet, had acquired Ravelston, an estate once belonging to the Keiths, from Sir Archibald Primrose of Dunipace, Stirlingshire, in 1726. The family claimed descent from Alexander Keith of Pittendrum, Aberdeenshire, fourth son of the third Earl Marischal (cf. Douglas, Peerage, ed. Wood, ii. 191, 198) . Robert Keith (1681–1757) [q. v.] disputed the claim of Alexander Keith of Ravelston to the headship of the Keith family in ‘A Vindication of Mr. ”
