Before this Earl succeeded he also was known as George Mackenzie of Kildun, hence the error in the Gruinard Genealogical Tree. The author of the Ancient MS., so often quoted in the course of this work, was a contemporary of John, I. of Gruinard, and he states that Earl George "had also "ane naturall" son, called John Mackenzy, who married Loggie's daughter." The author of the Ardintoul MS., who was the grandson, as mentioned by himself, of the Rev. Farquhar Macrae, Constable of Ellandonnan Castle in Earl Colin's time, and who died advanced in years as far back as 1704 - consequently a contemporary of John of Gruinard - describing the effects of the disastrous battle of Worcester, says that Earl George, who was then in Holland, was informed of the result of the battle "by John of Gruinard, "his natural son," and Captain Hector Mackenzie, who made their escape from the battle," that the tidings "unraised his melancholy, and so died in the latter end of September, 1651." The Letterfearn MS. is also contemporary, for the author of it speaks of Earl Kenneth as ""now" Earl of Seaforth," and of George of Kildun in the present tense, while he speaks of his father in the past tense, and he say's that "He (Earl George) left "ane natural son," who "is" called John, who "is" married with Logie's daughter." That John of Gruinard was married to Christina, daughter of Donald Mackenzie, III. of Loggie, is proved by a sasine dated 1655, in which that lady is described as his wife. It may be objected to these MSS. that, however probable it may be that they are correct, they are not necessarily authentic. But there is ample evidence of an official and incontestible character on the point. A sasine, dated 6th of February, 1658, is recorded in the Particular Register of Sasines of Inverness, vol. 7, fol. 316, from which the following is an extract - "Compearit personally John Mackenzie, "naturall" broyr to ane noble Erle Kenneth Erle of Seaforth Lord of Kintail, etc., as bailzie in that part," on behalf of "the noble Lady, Dame Isobell Mackenzie, Countess of Seaforth, sister german to Sir George Mackenzie of Tarbat, Knight, future ladie to the said noble Erle." Another authentic document having a most important bearing on this question was recently discovered in the office of the Sheriff-Clerk of Tain. It is a discharge by Patrick Smith of Braco, dated and registered in the Commissary Books at Fortrose, on the 4th of December, 1668, in which the parties are described as "Kenneth Erle of Seafort, Lord Kintail, as principal, and John Mackenzie of Gruinyard, designit in the obligatione vnder-wrytten his "naturall" brother, as cautioner." Further, George of Kildun married, first, Mary Skene, daughter of Skene of Skene, in 1661. This is proved by a charter to her of her jointure lands of Kincardine, etc. (see Particular Register of Sasines Invss., vol. ix. fol. 9). He married, secondly, Margaret, daughter of Urquhart of Craighouse.