Preheat the oven to 400 degrees. Lightly grease a large baking sheet. Combine flour, baking powder, salt, and soda. With a pastry blender, cut in butter, mixing it until the mixture resembles coarse crumbs. Whisk buttermilk and egg together, then add to flour mixture. Stir together until a soft ball of dough forms. Turn onto a lightly floured surface and knead gently, turning five or six times. Roll out dough with a floured rolling pin to about 1/2-inch thickness. Using a heart-shaped cookie cutter, cut scones out and place on the baking sheet. Brush the tops lightly with cream and sprinkle with sugar. Bake 10 to 12 minutes or until light brown. Serve warm with lemon curd, Devonshire cream, or preserves. Makes one dozen scones. For Devonshire Cream: Beat whipping cream, sugar, and vanilla until stiff. Fold sour cream into this mixture and refrigerate. Serve with warm scones.