Preheat the oven to 220°C Top & Bottom Heat. Low Added Steam.
Sift the self-raising flour, baking powder and salt into a bowl. Add the butter. Using your fingertips, rub the butter into the flour until the mixture resembles fine breadcrumbs and there are no obvious lumps of butter left.
Stir in the sugar, lemon rind and blueberries.
Make a well in the centre and add about ⅔ of the buttermilk and the sour cream. Use a knife to work the dough, adding a little more buttermilk as required to form soft but not sticky dough.
Sprinkle a little flour onto a work surface. Tip out the dough and pat with floured hands to smooth. Work the dough as little as possible or the scones will be tough. Pat out gently to about 2cm thick.
Use a pastry cutter to cut into rounds. Place on a baking sheet lined with parchment. Glaze with a little of the buttermilk.
Bake for 12-15 minutes depending on size. Remove to a wire rack to cool.