Put the meat joint in a roasting tray, season and add enough water to cover the bottom. This is important if you wish to make gravy from the juices. You may need to top up the tray during the cooking process.
Roast in a preheated oven (200c/400f/Gas 6) until the core temperature reaches a minimum of 75c (approximately 25 minutes per 450g (alb) plus an extra 25 minutes)
Leave to rest, covered with a piece of tin foil for 20 minutes before carving.
Remove the meat from the tin and drain off excess fat. Return the pan to the hob, add 750 ml of water and bring to the boil. Add a few ladles of base sauce to enrich. Mix 50g of flour with a little water and pass through a sieve into the gravy to thicken. Simmer of 20 minutes until happy with the consistency, strain, season and serve.