Thanks for the response. Ancestry.co.uk says that Robb is Scottish and Northern Irish short form for the personal name Robert. Which makes sense. I never really believed that Robb's were a sept of Clan Stewart of Appin. I have read on some websites and in one of my clan books that Robb is a sept of Clan Robertson and Clan MacFarlane. The Clan Robertson connection seems more likely mainly because of the name Robb and Robert.
My Robb's were from Carmav(e)y, Antrim, Ireland before they moved to Canada. Did the Plantation Robb's settle in the Antrim area?