Remove the turkey from the roasting pan and set aside to rest. You'll want to try to skim off and remove most of the fat from the surface of the turkey juices left in the roasting pan - sometimes it's easier to use one of those gravy separator jugs to do this.
Place the roasting pan with the juices over medium heat. Whisk in the flour for about 5 minutes. Then slowly add the stock and keep stirring to loosen all the tasty bits on the bottom of the roasting tin; bring to the boil, simmer for 5 minutes, then whisk in the redcurrant jelly. Season to taste with salt and black pepper.