Clan Grant uses the Gov. set #2, or Black Watch as their hunting tartan;usually attributed to the fact that one of the six original companies was recruited and commanded by Col. William Grant of Ballindalloch and after his death commanded by by the brother of the Chief of Grant, Major George Grant.
The tartan posted above (the one that looks very close to Black Watch with yellow and red stripes added) probably became attributed as the Grant hunting tartan during the Highland revival due to it being the tartan of the 1st Strathspey Regiment and perhaps the 97th Regiment of Foot as well. Both regiments were raised in the last decade of the 18th C. by Sir James Grant of Grant. All that aside, calling it "Grant Hunting Tartan" probably came from the Wilson's books rather than any common usage.

Not that any of that has any bearing on the MacLaren tartans...