This antique bit has steel cheeks with a dark patina.

The cheeks are similar to those of a IXth Lancer's bit. There is a bean shaped slot for the cheekpiece at the top and the curb hooks are suspended from small round holes. There are three slots in the section beneath the mouthpiece, a small one for a lip strap and two options for the curb rein. 

One cheek is stamped "Capt.Whatton's Combination Bit" and "Regd.No, 691535".

(This is probably Captain Stewart Montagu de Heriz Whatton, I can find various references to him in the Hurlingham Club's yearbooks from the 1920's)

The other cheek is stamped "Champion & Wilton 57 Oxford St."

The mouthpiece has a rotating (? stainless steel) sleeve with a central narrowed portion to accommodate the tongue.

Dimensions : Mouthpiece 4¼" (10.8cm), Maximum total width (8" (20cm) total cheek length  7½" (19cm)
Weight : 595g (1lb 5oz)