Beautiful warming / serving tray by Mappin & Webbs with a wooden handle that unscrews to access the reservoir for holding hot water, as a mechanism for keeping food warm and insulating the tray.
Founded in 1775, Mappin & Webb expanded internationally, became silversmiths to the UK sovereigns since 1897. The hallmark and use of "Triple Deposit" indicates this was made between 1890 and 1930, and the presence of the monogrammed "N" underneath a crown could very well indicate this was part of a royal collection, even if simply a duke, earl or a viscount. Unfortunately, no other hallmarks are present, save for a tiny "1" on the edge of the lid.
Triple Deposit means that a good quality plating was used in making this piece by electroplating deposits of pure liquid silver on the base metal which may be a mixture of metals containing mostly nickel.
This warming dish is 10.5 inches in diameter and 16 inches long including the handle. The rim of the bowl stands 4 inches high, and including the lid it's 8.5 inches tall. It has minor wear including imperfections and small, barely noticeable marks or dents. Some tarnish present as with all antique silver.