Enter what you are roasting and how heavy it is, and this works out the cooking time, the oven setting and how long to rest it. On an Aga you cook in the hot roasting oven and finish or hold in the cooler oven, so the times here suit both an Aga and a conventional range cooker.
What are you roasting?
Times are a guide based on standard minutes per kilo at a hot roasting temperature. Ovens vary, so use a meat thermometer for anything you care about: a probe in the thickest part is the only reliable test of doneness.