As a principle a roast should not be kept waiting and it should only leave the oven or be taken off the spit to be served immediately.
All roasts should be placed on a very hot dish lightly greased with fat from the roasting pan. It may be then garnished with bunches of watercress but this should only be done at the very last moment.
If the dish is going to be covered with a lid and kept waiting for a few minutes it should not be garnished. The roast gravy should always be served separately.
Roasts of meat and poultry should be arranged and served simply.