If you fancy doing as the Greeks do, the recipe is very easy:
Remove the intestines from the lamb. Wash it well and drain. Salt and pepper the inside of the lamb. Pass the spit through it so that the backbone is parallel to it. Tie it to the spit with thin wire or thick string so that it does not stir while you are roasting it. Tie the legs securely to the spit, sewing up the stomach cavity with some thick threads so that it will not open during the roasting time.
Baste the lamb with butter and lemon juice and sprinkle liberally with salt and pepper.
Heat the charcoal and allow the fire to settle. Place the spit in position.
Have close at hand a bowl of lemon juice and some olive oil and a basting brush and once the rotation has begun, start to baste the lamb often with the lemon juice and olive oil. You must rotate the lamb fast at first and then slow down as the meat starts to cook. Baste till the lamb is done and the skin is crisp.