Place all the dry ingredients, including the nuts, in a large bowl and mix together. In a separate bowl, mix together the egg and buttermilk, then stir into the dry ingredients.
Tip the dough out on to a surface dusted lightly with flour and form into a round about 20 cm (8 inches) in diameter. Mark into eight segments, then place on a baking sheet and dust with a little extra flour.
Place in an oven preheated to its highest setting and cook for 10 minutes, then reduce the heat to 200°C (400°F), Gas Mark 6, and continue to cook for about 15 minutes until the loaf is golden and sounds hollow when tapped.
Remove the loaf from the oven and transfer to a wire rack to cool.