Sift the flour, baking powder, bicarb and salt into a large mixing bowl.
Using your fingertips, rub the fat into the flour until the mixture resembles breadcrumbs.
Add sugar and stir with a spatula.
Add sultanas if using and stir again.
Form a well in the centre of the mix with your spatula.
In a small bowl beat the egg and buttermilk (or yoghurt and milk) and pour into the centre of your scone mixture.
Quickly pull the mix together - I tend to start mixing with the spatula and then go in with my hands to form the mixture into a ball.
The scone dough should be slightly sticky and soft. Add a little extra buttermilk if you find the dough a little dry.
Keep mixing to the absolute minimum.