2) Put the currants in a medium bowl and cover with hot water. Soak for 15 minutes.
3) Meanwhile, in a large bowl whisk together the flour, sugar, bicarbonate of soda and salt. Add the butter and rub into the flour mixture, until it is about the size of small peas.
4) Drain the currants. Add to the flour mixture with the buttermilk and mix until moistened and comes together in a shaggy dough.
5) Turn the dough out onto a floured work surface and knead lightly until just smooth, about 1 minute.
6) Form the dough into a ball and place on the centre of a lightly greased baking tray. Using a sharp knife cut a 1/2cm-deep cross into the top of the dough.
7) Bake until well browned and the bottom of the loaf sounds hollow when tapped lightly with your knuckles, about 1 hour.
8) Transfer the bread to a rack to cool completely before serving.