Place the raisins in a small bowl and pour over the lemon juice. Leave to stand for 10 minutes.
Meanwhile, place the lemon rind and flour in a large bowl, add the butter and rub in with the fingertips until the mixture resembles fine breadcrumbs. Drain the raisins, then stir in with the sugar. Using a palette knife, gradually mix in the milk to form a dough – do not over-mix or knead.
Turn the dough out on to a floured surface and press out lightly to about 2 cm (3/4 inch) thick, then cut out 12 rounds using a 4–5-cm (1 1/2–2-inch) plain biscuit cutter, using the trimmings as necessary.
Place on a baking sheet and bake in a preheated oven, 200°C (400°F), Gas Mark 6, for 12–15 minutes until risen and slightly coloured. Transfer to a wire rack to cool.