• Remove the joint from the fridge 1 hour prior to cooking. Mix the oil, rosemary, garlic, salt and pepper together in a small bowl (do earlier in the day to really infuse the flavours). Put the beef into a medium/large roasting tin, keeping the netting on if there is any. Then, using your hands, rub the rosemary and garlic oil all over the joint.
• Preheat the oven to 200ºc/180ºc fan/400ºf/gas 6. Transfer to the middle of the oven and roast for 1 hour or until the internal temperature of the thickest part reaches around 66ºc/150ºf (for medium-well done beef, see notes for other temperatures) or just 2-3º below, as the temperature can go up 5-10º while resting. Test with a food thermometer from about 20-25 minutes before cooking end (see notes) as all joints and ovens vary and it could be ready sooner.
• Rest the joint for 15-30 minutes, covered loosely in foil after 10 minutes. Then slice thinly, against the grain, and serve.

TO MAKE THE GRAVY

• Carefully pour the juices from the beef in the roasting pan through a sieve and into a small saucepan. Turn the heat to low, add in the gravy granules and stir well using a balloon whisk to dissolve. Pour in the hot kettle water and stir in well. Taste and add more gravy granules/mix or more water accordingly. Then leave the gravy to come to a simmer and bubble away for 3-5 minutes or until thickened to your liking. Don’t forget to also add the juices that have gathered under the resting beef into the pan.