Expose and cut out the wishbone. This makes the duck easier to carve once cooked. A butcher can do this for you.
Heat oven to 240C/220C fan/gas 9. Lightly score the skin of the duck all over, and make a deep cut from inside the body into each leg.
Season the duck well. Heat an ovenproof frying pan over a low heat. Hold the duck on its side using tongs and sizzle for 10 mins, until browned. Turn and cook on the other side for 10 mins more.
Turn the duck breast-side down, then transfer the pan to the oven and cook for 5 mins. Drain the fat from the pan, keep the duck breast-side down, and continue to roast for 10 mins.
Meanwhile, cut both oranges in half, then cut 4 wedges from half an orange. Heat a small frying pan over a medium heat, then cook the orange wedges in the dry pan for 1 min on each side to lightly caramelise.
Remove the orange wedges from the pan and set aside. Squeeze the juice from the remaining orange halves into the hot pan and reduce by half. Add the marmalade, take off the heat and stir together.
After 15 mins of roasting, turn the duck over and brush the marmalade glaze over and continue to roast for a final 10 mins. Rest for 20 mins.
Carve by cutting the leg and thigh away, then separating the leg from the thigh. Carve slices of breast and serve with the orange wedges to squeeze over.