Sift the baking powder, flour, salt and sugar into a large bowl. Cut the butter into this mixture until it resembles coarse meal. Add milk and form a soft dough. Pat out by hand on a floured board and form a circle 1/2 inch thick. Cut in wedges and either bake on a floured griddle over medium heat about 15 minutes or until lightly browned, turning once, or bake in the top of a preheated 375 degree oven for 15 minutes. Serve hot, split and buttered, with jam or, if cold, split and toast before serving the same way.