Sprinkle lamb with salt and pepper; place on rack in shallow roasting pan.
Bake in 325-degree oven for 30 to 35 minutes per pound or until meat thermometer registers 175 degrees for medium doneness.
Combine sherry, jelly, catsup and marjoram in small-saucepan; heat, stirring, until jelly melts.
Brush on lamb occa- sionally during last 1 hour and 30 minutes of baking time.
Heat remaining sauce; serve with lamb.
Garnish with parsley and lemon wedges.