Preheat the oven to Gas 6/200°C/Fan 180°C.
Line a baking tray with greaseproof paper the dust with a little flour and set aside.
In a large bowl, tip in the flours, baking soda and salt Use your fingertips to rub the butter into the flour until evenly dispersed.
Stir in the sugar.
Make a well in the centre of the flour and stir in the buttermilk until a soft dough is achieved.
Turn out onto a lightly floured surface and lightly knead for 1 minute until smooth, then bring together to form a flattened round about 5cm thick and 15cm across.
Place on the prepared baking tray.
Cut 2 slashes across the bread to make an ‘x’ and bake for 35- 40 minutes until well-risen and browned.
Place on a wire rack and leave to cool.