Preheat the oven 220°C/ 425°F/ GM7 and lightly grease 2 baking sheets (or use non-stick ones)

Put the flour, baking powder and salt into a large basin & mix. Add the butter and rub in

Stir the caster sugar through the flour mix, then add the lemon zest and blueberries. Toss briefly

Put the egg, buttermilk and 2 tablespoon of lemon juice into a jug and beat well. Reserve about 2 tablespoon of the liquid and add the rest to the mixing bowl. Stir, as gently as you can, with a blunt knife, to form a sticky dough. Try not to damage the blueberries too much. Add a little more liquid if necessary - it is better to have a wet dough than a dry dough

Once combined, turn onto a floured worktop and, using your hands, press the dough out to a thickness of around 2.5 cm (1 inch)

Use a straight edged circular cutter (6cm diameter) to stamp out scones from the dough. Dip the cutter in flour and plunge it straight down into the dough without twisting. This helps the scones rise evenly and hold their shape.Push the remaining dough together, knead lightly and use to press out a few more circles. You should get around 10 scones cut from the dough

Place the scones on the baking sheets and brush the tops with a little beaten egg

Quickly stir the caster sugar and lemon juice for the sugar glaze together. It will form a thick paste. Divide the mixture between the scones, placing a little on the top of each one. There is no need to spread it out

Bake for 10-15 minutes until well risen and golden

Allow to cool on a wire rack then serve with clotted cream and lemon curd or a lick of butter

Store in an airtight tin. Best eaten within 24 hours - preferably on the day of baking