Take the duck out of the fridge 2 hours before you want to start cooking it. This will allow it to acclimatise to the ambient temperature for even cooking.
Unwrap the cling film and then score a diamond pattern along the duck breasts. This will allow the fat to drip away from the duck and crisp the skin. Now prepare the spit and skewer into the duck. Ensure the duck is central on the spit.
Prepare the BBQ for indirect cooking. Use a full chimney of coal and then when the coals are ready, split them between the two coal baskets in your BBQ. Place the baskets either side of the BBQ and then place a drip tray in the bottom which will catch the fat which drips off the duck.
On the BBQ, set the vents to half open on the bottom and top vents to begin. We're aiming for an internal BBQ temperature of 200℃.
Place the duck on the BBQ rotisserie and let it start to cook. Check on it every 30 minutes to make sure it is turning properly and evenly cooking.
Cook the duck until the internal temperature reaches 74℃ at the thickest parts of the duck. This will be in the thigh and also in the breast. Test a few areas of the duck to ensure it is cooked fully.
Take off the rotisserie and sit the duck on a plate covered lightly in foil to rest for around 15 to 30 minutes. Slice and serve.