Is this an actual photo of William Wilberforce?

It's Friday the 13th! Last night we finally got our first real snow. And you know how it is in Ohio --- nothing by halves. It started snowing last night and hasn't stopped all day today. It's also very cold (had trouble making it above twenty) and windy. Elizabeth had to fill the bird feeders three times today!

Well, supposedly this stops by tomorrow late, and it's supposed to hit forty again early next week. We'll see how that goes. Tomorrow is the day that all the Christmas decorations come down, so we're figuring on a busy day. Dad's here to help, though, so it won't be bad. We're listing some things on eBay, so that's what I was up to this afternoon.

Got a bit of a puzzle, so I'll post it here and see if someone comes up with an answer. This is a picture that has been marked "William Wilberforce" in at least one book and several websites. Now, my question is: is this actually Wilberforce? If it is, then how do they know that and where did it come from? None of my searches have found any credits for the photo (apart from "Anti Slavery International", whom I have e-mailed) and no explanation. If this is Wilberforce, then why are people still wasting their book covers etc. with unfinished portraits and paintings? If this is a real photo, I would expect it to be more famous --- hence my reluctance to believe in its sincerity. If anyone knows the answer to this, I would certainly appreciate a response (via a Blogger comment). More later.