There is a "G" monogram on one side of each piece, as shown in my photos. It's well incorporated into the design and hard to see, especially on the smaller pieces. All three pieces bare the maker's mark on their undersides and all are quadruple plated with silver. All pieces are in fabulous condition with no damage whatsoever. The coordinating tray #1728 is marked "EPNS" indicating that it is nickel electroplated over silver.
I don't recognize the maker's mark, but this was apparently bought at the same time as the Derby set and it's also got a "G" monogram. This tray is a good, heavy weight nearly 2 lbs. And has a thick relief edge of grapes, leaves and vines. There are light scratches on the surface of the tray from its use under the tea set.
Measurements: Teapot: 9 tall, weight: 2 lbs. Cream & Sugar are both 4 tall and each weighs 10 oz. Tray: 13 diameter, weight 2 lbs.