2) Preheat oven to 240C/Gas Mark 9. Unwrap pork and place in a roasting pan with sides about 5-cm high. Cook 45 minutes until dark brown. Remove from oven. Lower oven to 160C/Gas Mark 3. Pour beer over the top and add chopped garlic around the pork. Cover tightly with heavy duty foil or twice with regular foil.
3) Poke about 10 holes all over the top of the foil. Cook pork butt 2 1/2 hours or longer until very tender. The meat should easily pull away from the center bone.
4) Place the meat on a plate and pour the pan juice (there will be plenty) into a saucepan. To the pan juices add tomato ketchup, Dijon mustard, Worchestershire sauce, and sugar. Bring to a simmer until reduced by half and thick, about 20 minutes.
4) While the sauce is reducing, pull apart the pork with 2 forks. Pour the sauce over the pulled pork and work through until fully absorbed.