The Weymouth doesn't come in olive calf.
Seriously though, I've been somewhat curious about this myself. The choice of last, leather, and widths put the Newbury ahead of the Weymouth, but the Weymouths cost half as much. Have you tried anything on the 337 last? Which last were you thinking of for the Newbury? RJman has a beautiful pair of plain-toe Newburys. Only pair I've seen on these forums, though several people seem to have the Weymouth.