Preheat oven to 350 degrees. Line two baking sheets with parchment paper.
Combine flour, sugar, baking powder and salt and mix well.
Cut in the butter until it is the size of small peas.
Add currants and orange zest and toss well.
Whisk together the egg and milk. Add to the dry ingredients and mix and fold until the dough masses and the flour is absorbed. Don't worry if the dough is a little streaky.
Divide dough in half and shape into two balls. Pat each one into a 6-7 inch circle on a lightly floured surface. Roll about 1-inch thick and cut like a pie into six wedges each.
Bake until golden brown and firm to the touch, 25-30 minutes. Best served warm.