Preheat oven to 190 degrees C. Lightly grease a large baking tray.
In a large bowl, mix together flour, sugar, bicarbonate of soda, baking powder, salt and butter. Stir in 250ml buttermilk and egg. Turn dough out onto a lightly floured surface and knead slightly. Form dough into a round and place on prepared tray.
In a small bowl, combine melted butter with 4 tablespoons buttermilk; brush loaf with this mixture. Use a sharp knife to cut an 'X' into the top of the loaf.
Bake in preheated oven for 45 to 50 minutes, or until a skewer inserted into the centre of the loaf comes out clean, about 30 to 50 minutes. You may continue to brush the loaf with the butter mixture while it bakes.