Method: Cream the sugar and margarine together, then add the semolina and flour. Knead as shortbread until smooth and then roll into a sausage shape in demerara sugar, coating evenly. Cut into slices and lay on a greased and floured baking sheet or tray. Bake in an oven preheated to 350 °F/ 180°C/Gas mark 4, for about 30 minutes. Leave on a wire rack to cool.