Creamed Haddock

From 1922:

Take 1 oz. dripping, 1 lemon, some browned breadcrumbs, and a ¼ pint of nice white sauce. Fillet the haddock, grease a baking tin with dripping. Set fish in this, squeeze the juice of half a lemon over it, season with pepper and salt, and cover with greased paper. Bake in a steady oven for 10 minutes. Make a gill of good white sauce, stir the liquid from the fish into it, boil up again, and season to taste. Place the fish on a very hot dish and pour the sauce over it. Scatter some browned breadcrumbs over and garnish with lemon sliced. Serve as hot as possible.