Preheat the oven to 220°C (200°C fan).
In a large bowl, sift together the self-raising flour and baking powder. Add the cold, cubed butter.
Rub the butter into the flour mixture using your fingertips until it resembles breadcrumbs.
Stir in the caster sugar and a pinch of salt.
Make a well in the centre of the mixture and pour in the buttermilk.
Using a round-bladed knife, stir the mixture until it forms a soft dough.
Turn the dough out onto a lightly floured surface and gently knead it a few times until smooth.
Pat the dough out to a thickness of about 2.5cm (1 inch) and, using a floured 6cm (2½ inch) round cutter, cut out rounds.
Place the scones onto a baking tray lined with parchment paper.
Brush the tops of the scones with a little milk.
Bake in the preheated oven for 12-15 minutes or until risen and golden brown.
Transfer to a wire rack to cool slightly before serving.
