Pre heat the oven to 200°C, 400°F, Gas Mark 6. Pierce the skin of the duck with a fork. Cut one apple into quarters and toss in 2tbsp of the Sage. Push the apple into the cavity of the duck. Place the duck on a wire rack inside a large roasting tin and sprinkle the surface with Sea Salt. Cook uncovered for 45 minutes.
Meanwhile, peel and cut the potatoes into chunks. Par boil for 10 minutes. Drain. Remove the duck from the oven, lift out the rack and drain some of the fat away. Return the duck to the roasting pan, without the rack, and scatter the potatoes around. Cook for 40 minutes.
Meanwhile, mix together the honey, mustard and sage. Cut the remaining apples into halves and toss in the mixture. Cook on a separate roasting tin for 25 minutes. When the duck is cooked, allow to stand for a few minutes before carving. Serve with the apples, steamed carrots, sugar snap peas and plenty of gravy. Garnish with sage.