Jenny, I believe the MacGregors had a conference in Perthshire to vote on whether the whole clan should adopt the name Grant. Their own name being proscribed and the tribe using Drummond, Campbell etc'. In view of the many connections between themselves and the Grants, the adoption of the name was agreed, one of these new Grant lairds being appointed head of the whole name. The laird of Grant's reaction to this must have been interesting. The idea was dropped.
I should think that the adoption of the surname Grant by the lairds own tenants was just a sensible move to avoid the chaotic situation of giving leases to people who used a patronymic.
Skoosh.