Cover the turkey in foil and roast for 1 hour LESS than the total time you have calculated. The foil will help keep the breast meat juicy and stop the skin browning too soon and burning before the meat is cooked.
Wen there is 1 hour remaining of the TOTAL TIME, remove the turkey from the oven and remove the foil. Baste the turkey with the juices you find at the bottom of the tin. Put the turkey back in the oven, uncovered this time, for a further 30 minutes.
After this 30 minutes, turn the oven up to 220C / 200C fan / gas mark 7 / 425F, remove the turkey from the oven and baste with the juices. Return the turkey back to the oven for a final 30 minutes. Cooking the turkey at a higher temperature will help the turkey skin to brown and crisp up. This is also the perfect temperature for roast potatoes, meaning you can start them now and they will be ready when the turkey has rested for 30 minutes.
After a final 30 minutes (the turkey will now have cooked for the TOTAL TIME you calculated in step 3), remove the turkey from the oven and check it is done. Stick a small sharp knife in the fattest part of the turkey (between the breast and the thigh), and the juices should run clear and the meat should be white. If you have a meat thermometer, the internal temperature should be 74C (165F).
Transfer the turkey to a clean roasting tin (or similar). Allow the turkey to rest for 30 minutes, uncovered. It will not get cold and the meat will taste much better for being rested. Not covering the turkey also ensures the turkey will not lose its crispy skin.
Total cooking times: 3kg/6.5lb turkey = 2h30, 4kg/9lb turkey = 2h50, 5kg/11lb turkey = 3h10, 6kg/13lb turkey = 3h30, 7kg/15.5lb turkey = 3h50, 8kg/17.5lb turkey = 4h10, 9kg/20lb turkey = 4h30, 10kg/22lb turkey = 4h50.
Suitable for freezing.
Nutrition information is approximate and meant as a guideline only.