Preheat oven to 200°C. Lightly grease an oven tray.
In a large bowl, sift flour, salt and sugar; rub in butter. Stir in milk and enough water to mix to a sticky dough.
On a floured surface, knead dough until just smooth. Place dough on oven tray; press into a 16cm round.
Cut a cross into top of dough, about 1cm (½-inch) deep. Brush dough with a little extra milk; sprinkle with a little extra flour. Bake about 45 minutes. Turn damper, top-side up, onto wire rack to cool.