Mix flour, baking powder, salt and the 1/2 cup sugar in medium bowl until well blended. Cut in butter with a pastry blender until mixture is crumbly. Toss in currants.
Beat egg and milk with a fork and add to flour mixture; mix gently with fork just until blended. Dough should be consistency of pastry dough.
Roll out dough to 5mm thickness with floured rolling pin on lightly floured pastry cloth or board. Cut with 8cm floured biscuit cutter.
Heat greased heavy frypan over moderate heat until few drops of water jump when dropped on surface. Cook biscuits a few at a time for 3 minutes, or until golden brown. Flip and cook another 3 minutes, or until golden brown on second side. Remove to wire rack. Sprinkle with sugar. Let cool completely, then wrap in plastic bags to store. Can also be frozen.