Combine flour and next 5 ingredients, stirring well. Cut in butter with a pastry blender until mixture is crumbly. Gradually add currants and buttermilk, stirring just until dry ingredients are moistened.
Turn dough on lightly floured surface and knead 4 or 5 times. Pat dough to 3/4 inch thickness and cut with 3 inch biscuit cutter. Place scones on lightly greased baking sheet, brush scones with milk and sprinkle with sugar. Bake at 400°F for 18 minutes or until golden.