A responsibly sourced mix of cod, smoked haddock, salmon, prawns & scallops in a luxurious vintage Cheddar and Gruyère cheese sauce, topped with a sourdough crumb and fresh herb topping M&S seafood gratin contains salmon reared in Scotland, wild caught cod and smoked haddock from the north east Atlantic, Scallops caught off the Argentinian coast. King prawns grown in Honduras.