Has anybody raised the question of Saint-Mémin's drawing of Clark actually being Clark? Every portrait I've ever seen of Clark represents him a little differently, but none so much so as Saint-Mémin's. If you isolate separate areas of the face they have almost no resemblance to any other portrait of Clark, especially in the nose. As an artist I can tell you this is one of the first features you have to get "right" in order to establish a likeness. In comparing the two noses in these portraits, it's almost impossible to imagine that either one of those two outstanding artists got theirs so wrong. Noses, unlike cheeks and chins, don't change much with the vagaries of weight loss and gain. Except for injury, only age will reshape a nose, but even then it usually just gets bigger.
It may have been documented beyond question that this portrait is indeed of Clark, and I wish I had more time to investigate. But I've stopped using Saint-Mémin's drawing as reference material for my paintings. I'm just too suspicious of the contrasts between it and the other portraits of Clark.