Forerib is good, as is sirloin if you are dry roasting (in an open tin). If pot roasting (in a closed dish), use topside, silverside, brisket, thick flank. Buy the best you can afford, and from a proper butcher if possible. Go for well aged, well hung beef of dark red colour, with marbling and a good outer layer of creamy coloured fat. Take the joint out of the fridge at least an hour before you want to cook it. In any case, you sprinkle with salt and pepper and a little dry mustard if you like. roast at the hottest temperature your oven will go to for 20 minutes, then turn it down to GM5/190C/375F. Count the cooking time from when you turn the oven down and allow 10-15 minutes per pound for rare meat, 20 per pound for medium and 25 for well done. Take the joint out of the oven at the end of the cooking time and cover with tinfoil and a thick cloth or towel and leave for at least twenty minutes to rest before carving. this gives you time to turn the oven back up to get the yorkies in, to brown the roast spuds if they're not brown enough, to get the gravy made and cook the accompanying vegetables. it also allows the juices to stay in the meat, giving a more tender joint.