Preheat the oven to 375°. In a large bowl, whisk the flour with 3 tablespoons of sugar, the baking powder and salt. Using a pastry blender or 2 knives, cut in the butter until it resembles small peas. Stir in the currants and lemon zest. Add 3/4 cup plus 2 tablespoons of the cream and stir until the dough is evenly moistened. Gather the dough into a ball and gently knead it a few times.
On a lightly floured work surface, pat the dough into a 1/2-inch thick round. Using a 2 1/2-inch round biscuit cutter, stamp out as many scones as you can. Gently gather the scraps, press them together and cut several more scones. Transfer the scones to a baking sheet. Brush the tops with the remaining 2 tablespoons of cream and sprinkle generously with sugar. Bake in the lower third of the oven for about 25 minutes, or until the scones are golden and cooked through. Let cool slightly before serving.
The scones can be stored in an airtight container for up to 2 days.