Brush a 23 cm x 32 cm (9 inch x 12½ inch) Swiss roll tin generously with oil.
Sift the flour, bicarbonate of soda and salt into a large bowl. Stir in the chopped rosemary and sun-dried tomatoes. Make a well in the centre, add the buttermilk to the well and gradually stir into the flour. Bring the mixture together with your hands to form a soft, slightly sticky dough.
Tip the dough out on to a lightly floured surface and lightly knead for 1 minute, then quickly roll into a rectangular shape to fit the prepared tin. Press the dough gently into the tin, then brush with oil. Using your finger, make small dimples in the top of the bread. Scatter over the black olives, rosemary sprigs and sea salt.
Bake in a preheated oven, 220°C (425°F), Gas Mark 7, for 15 minutes until brown and crisp. Brush with a little more olive oil and serve warm.