Vintage Silver Plate Small Covered Dish Three Pieces - 6" Round Martin Hall & Co

Martin, Hall & Co Sheffield Covered Butter Dish Caviar Bowl Silverplate 3-Pieces Base, removable serving piece, lid - three pieces Small, silver plate, Approx 6" in diameter and 5" tall overall Light signs of wear and patina - mostly the center portion of the removable round dish Weighs approximately 15 oz Not sure what all of the Hallmarks mean - photo attached