Preheat oven to 200 C / Gas mark 6. Secure roast with cooking string.
Make 8 slits around the roast about 1cm deep and insert 1/2 garlic clove into each slit. Sprinkle with fresh ground pepper. Place on a rack in roasting tin.
Roast in preheated oven for 20 minutes. Reduce heat to 160 C / Gas mark 3, and insert meat thermometer into roast. Continue cooking about 1 hour, or to desired doneness; remove from oven. Loosely cover with foil, and let roast stand 15 minutes before slicing.
To serve, slice very thinly, and use the meat drippings for gravy.