Yes, I have noticed the same thing about the nose. I have two professionals at the moment, both from the 60's I think, that are remarkably different around the nose. Aside from that, the metal BROOKS badge on the back is different, the rivets are different, and the shape is different. The later? one is narrower across the middle; that is, it's shaped more like a Y than a V. This difference is only in the leather, though; they appear to be on the same frame.

Incidentally, that brings up an interesting point, about the frames. I have Wrights saddles in two different models, a W3N and a W3SW, that look very different from above but are clearly built on the very same frame. But all the Brooks B17's I have are on different frames. For example the 1950? is black and has bag loops; the 1959 is chromed and has no bag loops; the 1967 is black and has no bag loops; and the 2008? is chromed and has bag loops. And it's wider; I suspect the other three are all "narrow"s. A B15 of uncertain date appears to have exactly the same frame as the 1959 B17.