Tartans not of your lineage

[ThistleDown]

Many faux pas occur in the New World (and indeed in Scotland, too) when it comes to tartan and TCHD. To be correct, he should not wear the Mackenzie and either wear his own tartan or a universal or regional one and show his commitment to his friend that way. But there's no law that says he must, so on some sort of faux pas scale this is probably at the lower end.