This 7-1/8" soup spoon appears to have a Polish hallmark inside the bowl, but I cannot find anywhere if Polish pieces were stamped inside the bowl or on the reverse of the handle. The hallmark is a "3" person's profile "W", which would appear to be .800 silver.
It's Polish spoon from Warsaw ("W"). Polish spoons were stamped inside a bowl very often. Letters MP stand for Mojżesz (Moses) Princenthal, silversmith from Warsaw.