There's a good possibility it is William Mill of Montrose, who was working 1815-25, sent some to Edinburgh for assay, but quite a lot of Provincial items were only partially hallmarked pre-1820.
Possibly Graham & Gordon of Madras 1794 - 97? Hugh Gordon was a watchmaker and jeweller, went into partnership with a Mr Graham who may have been from India. See Wynyard Wilkinson's Indian Colonial Silver.