Source: Johnston, Alexander, Jr., Genealogical account of the family of Johnston of that ilk, formerly of Caskieben, in the Shire of Aberdeen, and of its principal branches. Edinburgh, 1832.
The surname of Johnston is of great antiquity in Scotland, and must be familiar to everyone conversant with the history of that kingdom. The lineage of this race was of old proverbially honourable; in the ancient rhyme on the characters of Scottish families, to this day popular in some parts of the country, they are designed the gentle Johnstons.
The description of the line of the Lairds of Caskieben, and their alliances, from Stiven Johnstoun, sone to the Laird of Anandail, the first of that surname that possest Caskieben, to John Johnstoun, now heritable possessor thereof. Albeit God has not so multiplyed the neam of Johnstoun depending of Caskiben, as others that are not so ancient, yet of his great mercy, he has preserved ane continual and unbroken succession by lineal descent in that house, by the space of well near of three hundred years.
The two families of Johnston of that Ilk, and of Caskieben and Johnston of that Ilk in Annandale, long disputed the title to the chiefship of the name. The pretensions of the latter proceeded on the assumption that Stephen de Johnston, the founder of the family of Caskieben always maintained that he was the head or chief of the name. On this point, Douglas in the Peerage of Scotland, merely says; "There were two families of this surname, who both designed themselves by the title of that Ilk, viz. those of Annandale in the South and Caskieben in the North; but we cannot pretend to connect them with one another."
Stephen arrived in the North in the time of King Davis Bruce, who reigned from the year 1329 to 1371. Stephen de Johnston/e was a man of great learning, which was so rare in those days that he was honoured with the title of "the Clerk" - a designation to which, at that period, the clergy alone were considered to be entitled.
"For troubls wherein he fell in his owen countrie, he cam into the north pairt of Scotlande, and was pleasnatlie received by the Earle of Marr, to whome hee became secretarie."
Stephen married Margaret, daughter and heiress of Sir Andrew Garioch [sic] of Caskieben in Aberdeenshire, Knight, by whom he received a large estate, consisting of the lands of Johnston and Kinbroun, during the lifetime of Sir Andrew, after whose death, he, by right of his wife, succeeded to the lands of Caskieben, Crimond, Cordyce, and others, situated in the parishes of Dyce, and Caskieben or Monkeggy (now Kiethhall).
"Caskieben became then the chief title of his family; and of him all the Johnstons in the north are said to have been descended."
"The bearns gotten betwixt Stiven and Margaret Garioch (except the successor John), wee know not, neither the bearns of their sucessors to the third generation, because of the great antiquity and few monuments observed in these dayes." (The family of Garviehaugh or Garuiach, now Garioch, into which Stephen married, was of high antiquity in the north. Andrew de Garuiach was Sheriff of the County of Aberdeen 1264).
The name was anciently spelled de Johnestoune or de Johnestoun since the 1730's it was only informally spelled Johnston in Scotland.