In a bowl, whisk together the flour, sugar, baking powder and salt. Grate the frozen butter using a box or cheese grater. Add to the flour mixture and combine using a pastry cutter, two forks or your fingers until the mixture forms coarse crumbs the size of peanuts.
In a bowl, whisk together the cream and egg. Set aside a tablespoon of the mixture, this will be used to brush over the scones later. Pour the egg mixture over the flour mixture and mix until everything is just moistened.
Lightly flour your work surface and then turn the dough onto it. Press the dough together gently until it clings together in a ball. Using your hands, pat down into round disc which is 8-inches in diameter. With a sharp knife, cut into 8 wedges.
Line a baking tray with parchment or baking paper and place the wedges 1 inch apart.
Brush the scones with cream and place in the fridge for at least 30 minutes.
Pre-heat the oven to 220°C/200°C fan/425°F/gas 7.
Bake for 17-20 minutes until golden brown. Transfer to a wire rack to cool slightly.