Preheat your oven to 220 degrees Celsius (gas mark 7).
Roast your meat at this temperature for 30 minutes.
Reduce the oven temperature to 180 degrees Celsius (gas mark 3-4) and continue to roast the meat at a rate of 20 minutes per lb in weight. For example, a 2kg joint of lamb or beef will require 30 minutes at the high temperature with a further hour of cooking time.
With beef and lamb, some may prefer the meat to be served a little rare. You can adjust the time accordingly.
If you are unsure of how rare the meat is at core, stick a skewer into the meat to see how much blood still runs from the joint.
Always allow resting time for the meat before you carve and serve (about 30 minutes).