All timings are approximate and adjustments may be required based upon your oven. Remove joint from fridge at least 20 mins prior to cooking. Cook joints with a natural fat coverage, fat side uppermost. Rare 20 mins per 450g/1lb + 20 mins Medium: 25 mins per 450g/1lb + 20 mins Well done: 30 mins per 450g/1lb + 25 mins Cook at 190c/375f/Gas 5. To rest loosely cover foil for 20 mins.