Preheat oven to 425°F. Sieve flour, baking powder and salt into a large bowl. Stir in sugar.
With your hands, rub the butter into the flour until it resembled course breadcrumbs.
With a whisk or fork, mix the egg into the buttermilk.
Create a well in the middle. Slowly add the buttermilk until you have a soft dough. It should just come together and you should be able to handle it without it being really sticky.
Place the dough on a floured surface and knead a couple of times just to remove any cracks. If the dough is too sticky, add more flour.
Roll out to around 1 inch thick and cut with a cutter or glass dipped in flour.
Place on a floured/buttered baking sheet (or use parchment paper). You should get about 12 scones.
Brush each scone with milk to help brown the tops when baked.
Bake for 10 - 15 minutes or until the scones are golden.
Best served immediately but can be warmed the following day or eaten cold.