Looking in Susan Tobin's book, and comparing with this one, Wedgwood ducks appear to have less of the Disney humorous stylization, and seem to be just a little more realistic. Trouble is that ducks and whatever other animals etc., have been made by so many producers.
Perhaps Rosie might have some thoughts on this piece.
P.S. the fact that an animal lacks a backstamp wouldn't, on it's own, be a reason for discounting Wedgwood......... it's not uncommon to find their pieces without a mark. Seem to remember that Christine says those without a mark are seconds from the shop, I think.