Sift together flour, baking powder and salt, and add the grated or chopped suet. Stir in enough cold water to make a pliable dough, and line a pudding basin with two-thirds of the pastry. Cut the flesh of the grouse into neat chunks, stewing the bones and trimmings in water to make a good stock. Brown the grouse and cubes of steak in the butter and put into the basin with salt, pepper and a pinch of nutmeg, chopped onion, and enough stock or water to half fill the basin. Cover with the top crust, put on paper and a cloth, and steam for three hours, adding boiling water to the saucepan to keep it almost to the top of the basin. Make a hole in the top crust before serving and pour in hot stock or gravy.