Here we have a 1927 Mappin Campaign silver cased trench style watch. It has a well sized 35mm case with the fixed bar lugs. The enamel dial is original with the red 12 and 'Mappin Campaign' signing. The hands are of spade and whip style and are thermally blued. The sub-second hand is also original. There are hairline fractures to the dial and the Campaign signing is worn. 
The crown appears original but is slightly bent. The hinge to the case back is broken but the back snaps on and stays in place. The inner hinged case back hinge is good. 
The case has hallmarking for sterling silver from Edinburgh assay office dating to 1927. It has the Mappin and Webb makers mark to the case.
The movement is a good quality 15 jewel calibre by Fontainmelon. The balance is good, the escapement is stuck. Fully wound.

It is sold as spares and repairs. Any questions, please ask!