Preheat the oven to 400°F (207°C). Mix the egg wash ingredients together and set aside.
Place the butter, flour, baking powder, sugar, and a pinch of salt into a mixing bowl. Use your thumbs and forefingers to break up the butter and rub it into the flour until you get small, cornflake-sized pieces.
Make a well in the center of the dough, then add the eggs and milk, stirring with a spatula. Gently fold in the blueberries and raisins and add a tiny splash of milk if needed, until the dough becomes soft and slightly dry.
Move it around as little as possible to form a scruffy mass—at this point, you’re done. Sprinkle some flour over the mixture, cover the bowl, and place it in the fridge for 15 minutes.
Roll the dough out on a lightly floured surface until it’s about 1 inch (2.5 cm) thick. Using a 2.5-inch (6 cm) round cutter, cut out circles from the dough and place them upside down on a baking sheet for better rising. Re-roll any scraps to use up the remaining dough.
Brush the top of each scone with the Egg Wash twice and bake in the oven for 15-18 minutes, or until risen and golden. At that point, take them out of the oven and leave them to cool down a little. Serve with clotted cream (preferred), fruit jam, lemon curd, or butter.