1. Preheat the oven to 190°C fan (210°C/gas mark 8) and place a baking tray inside to warm.
2. Add the lemon juice to the milk and set aside until it begins to separate.
3. Tip the flour, salt, baking powder, cayenne pepper and mustard powder into a large bowl and loosely mix them together.
4. Add the butter and rub it into the dry ingredients with your fingers until the mixture looks like breadcrumbs.
5. Make a well in the centre of the dry mix and pour in the milk, fresh chives and most of the cheese (save some to sprinkle on the finished scones).
6. Use a knife to bring the mixture together, until it starts to form into large lumps.
7. Use your hand to squeeze the scone mixture into one soft ball, being careful not to overwork the mixture, before turning it out onto a lightly floured work surface.
8. Rather than rolling out the mixture, very gently press out the scone mixture to a depth of around 2-3cm.
9. Use a floured 5cm round pastry cutter to cut out your scones, ensuring that you do not twist the cutter as you cut.
10. Press any remaining mixture back together and repeat until it is all used up.
11. Brush the tops of your scones with beaten egg, ensuring that you do not allow it to run down the sides (as this can inhibit the rise).
12. Dust the preheated baking tray with a little flour and add the scones, topping them with a sprinkling of salt and cracked black pepper, and the remaining cheese.
13. Bake in the preheated oven for around 15 minutes until well risen and golden.
14. To serve, cut or tear the scones in half, topping each half with a generous serving of real butter.
Your scones are best enjoyed on the day of baking (ideally fresh from the oven), but they can be kept in an airtight container for 2-3 days. To refresh them before serving, place them back in the oven at 140°C for a couple of minutes.