1. Preheat oven to 200C (Gas Mark 6).
2. Roast for 20 minutes at 200C (Gas Mark 6).
3. Reduce oven temperature to 180C (Gas Mark 4) and continue to roast for:
42 Minutes Per Kilo
4. Remove the joint from the oven and rest for 20 minutes before carving.
Please Note, the above is only a guide and ovens may vary in temperature.