Preheat
the oven to 350°F/180°C/gas 4. Butter a
deep 8-inch (20-cm) cake pan.
Sift the flour, baking powder, and salt into a
medium bowl.
Beat the butter and sugar in a large bowl with an
electric mixer at high speed until creamy.
Add the eggs and vanilla, beating until just
blended.
Mix in the dry ingredients and currants.
Spoon the batter into the prepared pan.
Bake for 1 hour 20 minutes, or until a toothpick
inserted into the center comes out clean.
Cool in the pan for 5 minute.
Turn out onto a rack and let cool completely.
Dust with the confectioners' sugar before serving.