To make the marinade mix together F. Whitlock & Sons BBQ Mustard Thick Sauce, garlic and Bourbon.
Place pork in a tray and pour over marinade. Turn meat to ensure it is well coated. Cover and refrigerate for 1-2 hours, or overnight if wished.
Preheat oven to 150°C (fan assisted). Remove pork from the marinade. Reserve the excess marinade for using as a glaze later. Place a large piece of foil in a roasting dish. Lay the pork on the foil. Place the rosemary sprigs on the pork. Wrap the foil around the pork. Bake for 2 hours. Remove the pork from the oven. Increase the oven temperature to 200°C (fan assisted).
Remove the pork from the foil. Remove the rosemary. Place a wire rack in the roasting dish and sit the pork on the rack. Brush with the reserved marinade. Return the pork to the oven and cook a further 10 minutes, until the pork is glazed and cooked. Remove and allow to rest while cooking the potatoes.
Place potatoes on a low sided greased baking tray. Gently crush each potato with a potato masher or fork. Whisk together melted butter, olive oil and garlic and brush over the potatoes. Sprinkle over salt and rosemary leaves. Roast for 20-25 minutes, until potatoes are golden and crisp.