Pre-heat your oven to 200C Fan/220C/425F/Gas Mark 7
Put the self raising flour, baking powder, salt and caster sugar in a large mixing bowl and stir together
Add the butter in small cubes or chunks (or you can grate it in) and rub the mixture together with your fingertips, or pulse in a food processor, until the butter is fully combined and the mixture resembles breadcrumbs
In a jug, add the milk and lemon juice, leave for a couple of minutes until the milk goes lumpy. Then whisk in the egg and vanilla extract
Pour the milk mixture into the flour mixture, then mix it in to form a dough
Tip the dough out onto a floured surface and pat it together as briefly as possible by hand to about 2cm thick
Cut out rounds using a 2.5 inch cutter, push the cutter down and do not twist it. (You can make the scones bigger or smaller if you like by using different size cutters.) Re-shape the dough when needed until it runs out, but try and handle it as little as possible
Put the dough rounds onto a lined baking tray and glaze the top with the beaten egg. Bake for 12-14 minutes until the scones are risen, golden brown and sound hollow when tapped on the bottom
Cool on a rack and then slice or break in half and serve with jam and clotted cream, or any other topping of your choice
Best served on the day they are made, but can be eaten within 2-3 days. Can also be frozen