I quite like Clarkson anyway but also feel he could well have been a good choice.
I suspect the people who are discounting him out of hand may have not seen any documentaries he's presented.
I recall Brunel, in the 100 Greatest Britons series, one about the Arctic convoys and another about the raid on St. Nazaire.
They were all excellent.
I'm quite impressed with James Holland, who somebody mentioned earlier, but a presenter that says "wiv" really grates!