Preheat the oven to 375 degrees F (190 degrees C) and place rack in center of oven. Line a baking sheet with parchment paper and set aside.
In a large mixing bowl place the flour, sugar, salt, baking soda, baking powder and whisk to combine. Add the butter and using two knives or a pastry blender cut in the butter until it resembles coarse crumbs. Add the rolled oats, dried cranberries and zest. Mix until combined. Stir in the buttermilk (adding more buttermilk if necessary) and mix just until the dough comes together.
Transfer to a lightly floured surface and knead the dough four or five times and then pat, or roll, the dough into a circle that is 7 inches (18 cm) round and about 1 1/2 inches (3.75 cm) thick. Cut this circle into 8 triangular sections. Place the scones on the prepared baking sheet. Make an egg wash of one beaten egg mixed with 1 tablespoon milk or cream and brush the tops of the scones with this mixture.
Bake for about 15 – 18 minutes or until lightly browned and a toothpick inserted in the middle comes out clean. Remove from oven and transfer to a wire rack to cool.
Makes 8 scones.
I just made six big ones but wow they tasted so good with my afternoon tea.