I agree with FCQ - no eggs in plain scones, and only plain scones if you're going to be eating them with jam and cream.
200g SR flour, scant 1 teaspoon baking powder, 50g butter, milk to mix. Rub butter into sieved flour and baking powder and mix to a soft dough with as much milk as needed. As a concession to modernity I will allow buttermilk or sour cream!
The dough should be softer and wetter than pastry, but not sticky; knead very briefly - 30 seconds or so - to get a smooth dough. Pat out dough on a floured board to 2-3cm in depth and cut into shapes as desired - don't twist the cutter if cutting out with cutters rather than a knife. Reroll trimmings, but don't expect scones from subsequent rollings to rise as much as the first ones cut. Put on non stick or lined baking tray and brush top with milk. Bake at 200C until risen and golden. Eat while still warm and pull apart so that the centre doesn't go doughy when a knife cuts through.
Tip from Great British Bake Off - if you brush with milk or egg wash, don't let it run down the sides, as it seals the dough into position and stops rising.
Tip from most scone makers - work fast and handle the dough as little as possible. I aim to have scones in the oven within 10 minutes of adding liquid to the flour.
If you are making rich scones add 25g sugar, 50g dried fruit, spices or citrus zest to taste and you can use an egg in place of some of the milk.