When the lamb is boned, ask the butcher to remove the bones and crack them. Combine the bacon, garlic, parsley, and basil in a food processor or use a blender. Blend the ingredients to a fine puree. Sprinkle the lamb inside with salt and pepper. Spread the bacon mixture inside the lamb to fill it. If some of the stuffing oozes out, no matter. Sew up the lamb, tucking in torn pieces as necessary. Sprinkle the lamb all over with salt and pepper. Rub the lamb with any excess bacon and herb mixture. Place the lamb, fat side down, in a heavy casserole and arrange the bones around it. The lamb and bones should fit snugly inside the casserole. Brown the lamb on all sides and sprinkle onion and carrots around it. Cover and cook for about 5 minutes. Carefully pour off and discard all fat that has accumulated. Add the wine, tomatoes, salt and pepper. Cover and bring to the boil. Cook and bring to the boil. Cook over moderate heat for about 2 hours. Remove the lamb and strain the sauce into a saucepan. Bring to the boil and skim the surface as necessary to remove as much fat as possible. Cook the sauce down until it is properly concentrated and sauce-like. Slice the meat and spoon a little of the sauce over each serving.