Preheat an oven to 190 degrees C. Lightly grease a baking tray.
Whisk together the flour, baking powder and salt in a mixing bowl. Cut the butter into the flour mixture with a knife or pastry blender until the mixture resembles coarse crumbs. Whisk together the egg, milk, sugar, lemon zest, lemon juice, and ginger in a separate bowl; stir into the flour mixture until moistened.
Turn the dough out onto a lightly floured surface and knead briefly for five or six turns. Pat or roll the dough out into a 1cm thick round. Cut into 8 wedge-shaped pieces and place onto the prepared baking tray.
Bake in the preheated oven until golden brown, about 20 minutes.