Preheat oven to 350°F.
Butter 2 baking sheets.
Place oats in large bowl. Sift in flour, sugar, baking soda and salt. Using your hands, mix in shortening until mixture resembles coarse meal. Gradually, add buttermilk; stir until dough forms. Transfer dough to floured surface. Roll out to 1/4-inch thickness. Cut out rounds, using 2 1/2-inch round biscuit cutter.
Arrange on prepared baking sheet
Gather scraps, reroll and cut out additional rounds.
Bake oatcakes until edges are pale golden, about 12 minutes. Transfer baking sheets to racks and cool for 5 min. then remove oatcakes to racks and cool completely.