Preheat oven to 500*F. Cut deep slits in top of roast and insert garlic slices. Salt and pepper the meat well. Lay a few fat slices under the roast, put it in preheated oven, and roast 20 minutes or so until the fat browns.
Turn the heat down to 300-325*F. and roast about 2 1/2 hours. When done, remove roast and the fat cracklings to a hot pan or platter.
Retain 2-3 tablespoons of fat in the roasting pan with the drippings and in it saute the finely chopped onions and celery. Stir in the flour and herbs. Stir on a low flame until thickens, stir in the herbs. Add Worcestershire sauce.