1lb boiled potatoes (not new potatoes, a good floury potato with a bit of taste like a King Edward or a Kerr's Pink)
Salt to taste I usually boil the potatoes with salt but the addition of the flour will lessen the salt flavour. So you need to add salt to taste, too much is not good but too little is bland.
2 oz butter
4 oz plain flour
Mash the potatoes with the butter and leave to cool before adding the flour to form a soft dough. Turn onto a floured surface in hand sized balls and roll flat to 5mm or your desired thickness. Cut each plate sized round in quarters and cook on a medium heat on the girdle. You can experiment with the heat as you go to get the desired browning either side. Don't be tempted to use too much flour to roll them out or to dry up the mix or they will be a bit leathery and too bready tasted. The quality is in a good dry potato, well drained. It's always better to have your potatoes cooked and left to go cold before mashing and the best idea is to make extra mashed potato when you are having it with your diner and keep it in the fridge for a few days till you are in a scone baking mood.
A good tattie scone with butter and black currant jam and a cup of good tea is a thing worth working for. The things you'll buy at the supermarket or so called home bakers are a waste of good jam.