Preheat the oven to 220°C/425°F/Gas mark 7. Flour a baking sheet. Sift the flour, salt, bicarbonate of soda and cream of tartar into a bowl. Rub in the butter until the mixture resembles fine breadcrumbs. Gradually stir in just enough milk to make a light, spongy dough.

Turn the dough on to a lightly floured surface and knead until smooth. Roll to 2½cm/1in thick. Cut into rounds with a floured 5cm/2in cutter.

Place the scones on the prepared baking sheet and brush the tops with milk.

Bake for 7-10 minutes until the scones are well risen and golden brown.