It's Clark, not Clarke. Trust me, I used to have a part-time job in bike sales, there. John Clark has pretty much retired these days and the company is headed up by his son, Chris.
They're perhaps not quite as big as Arnold Clark but they do have numerous car franchises across Central Scotland and in Aberdeen.
My wife, son and I have bought 5 cars and 5 bikes from them in the past 14 years.
They must have done something right, although when I ask how many I have to buy before I get a free one...