what temp do you cook a roast at?
Calculate your cooking time for medium-rare with 20 mins per 500g, or for medium use 25 minutes per 500g. For beef on or off the bone cook it at 240C/220C fan/gas 9 for 20 minutes, then turn down to 180C/160C fan/gas 4 (not forgetting to take this 20 minutes off the timing you have just calculated).