It is, I agree, amongst his best. It's so good in fact that though I am not a fan of Camilla, I think she looks gorgeous and attractive here.
Unfortunately, when you get close to perfection, minor flaws become more nagging than they would have been otherwise. Case in point, there is something a little off about the two pictures of Camilla in the left side of the banner. Can't quite put my finger on it, but their proximity invites comparison--almost as if they are standing on the same plane, one being several feet closer to the viewer of course; don't know how to fix it. Maybe if the front one was a little more to the left or back one more to right/or lower. Or if you cut the back one a little higher, so you don't see the shoes and the floor.
Take home message? Excellent work, as close to perfection as it gets.
And I am well aware of how much easier it is to analyze/criticize than to create a great banner.