Make the scone dough: Combine flour, baking powder, sugar and salt in a large bowl. Add soft butter and rub it in with your fingertips or use a hand mixer until it resembles coarse crumbs and it is well incorporated. Make sure there are no large lumps of butter. Mix in lemon zest.
Whisk together milk, egg and lemon curd in a small bowl. Make a well in the center of the dry ingredients and pour in the milk mixture. Fold together gently using a spatula until just moistened enough to come together. Add the blueberries and fold them in. Do not over-mix. The dough will be quite soft and sticky but resist adding more flour.
Generously dust your work surface with flour and turn the mixture out onto it. Fold it over just once or twice (max!) - do not knead. Sprinkle the soft sticky dough with more flour and pat it down so it is 8 inches by 6 inches pressing in loose bits as necessary. Brush off excess flour with a pastry brush and then cut into 8 pieces.
Transfer each scone to a parchment lined baking tray and brush tops lightly with milk. Bake for 7 minutes. Reduce temperature to 350°F and continue baking for 13 minutes or until evenly golden on top and on the bottom. Transfer scones to a wire rack to cool before adding the glaze.
Make the glaze: combine powdered sugar, lemon juice and milk in a small bowl and whisk until smooth. It should be opaque white and quite thick but thin enough to drizzle. Spoon it generously over each scones. Let it set for about 14 minutes and enjoy!