There can be little doubt the county of this clan was the Lennox district, where we find them yet in considerable numbers. The oldest account of them is given by Buchanan of Auchmar, 1723. He asserts the chief sept of the Lennox MacKinlays descends from Buchanan of Drumikill.
After mentioning that the Risks are the first cadets of the Drumikill family, he says: "The second cadets of this kin are the Mackinlays, so named from a son of Drumikill called Finlay; those lately in Blairnyle and about Balloch are of this sort, as also those in Bamachra and above the Water of Finn, in Luss parish. The Mackinlays in some other parts of these parishes are MacFarlanes.
Like so many Lennox clans, notably their far-off cousins of the Clan MacAuslane, some of the Mackinlays no doubt went over to Ireland at the time of the "plantations" in the 17th century. Hence come the Mackinlays and Macginlays of Ireland and latterly of America.
it is a common mistake to regard the clan ancestor as Fionnlagh Mor, progenitor of the Farquharsons of Braemar. The Farquharsons as a clan are called in Gaelic Clann Fhionnlaigh but the surname MacFhionnlaigh has never come to be used in English form. In fact, the surname has been constantly Farquharson, and there were no Mackinlays at all in Braemar or its vicinity.
The small clan Finlayson of Lochalsh are known in Gaelic as Clann Fhionnlaigh, and they, too, claim a traditional descent from the Clan Finlay of Braemar. It is probable the name Mackinlay embraces some of the Macleay clan. Some of the modern Mackinlays insist on accenting the "lay" of the name.
[Sir Thomas Innes of Learney, Lord Lyon King of Arms,
in "The Tartans of the Clans and Families of Scotland," 1938.]