Pre-heat the oven to 220C/425F/Gas 7.
Sift together the flour, baking powder and salt into a bowl. Stir in the sugar, add the butter and rub quickly into the flour, creating a fine breadcrumb consistency.
Add the milk, a little at a time, working to a smooth dough.
This is now best left to rest for 5-15 minutes before rolling.
Roll out the dough on a lightly floured work surface until 2cm/¾in thick. Using a 5cm/2in pastry cutter, cut the dough, using one sharp tap and not twisting the dough as you cut. Twisting the scone mix will result in an uneven rising.
Once cut, the scones can be either brushed with the beaten egg for a shiny glaze, or dusted with the flour for a matt finish.
Place the scones on a greased baking tray and bake in the pre-heated oven for 10-12 minutes until golden-brown. Allow to cool slightly, and serve while still warm.