Last week I picked up a builder plate at an antique fair outside London. From what I have been able to determine it is from an early group of Baldwin narrow gauge locomotives shipped to England during WW1. The locomotives designated 10-12-D. These were tank engines with a 4-6-0 wheel arrangement. They were used to shuttle supplies to the front lines in France. Couple of Wikipedia articles:
Appreciate any additional or corrected insight others might be able to share. Piece looks authentic; but wouldn't be upset if a copy given what I paid.