Pour off all but two tablespoons of fat and juices from the roasting tin and set it over a medium heat.
Sprinkle in the flour and stir for 1 to 2 minutes, scraping up the browned bits, until it forms a nutty paste.
Pour in the wine, if using, and let it bubble for a minute.
Gradually whisk in the hot stock, a little at a time, until smooth.
Add the Worcestershire sauce and redcurrant jelly, bring to a simmer and cook for 5 to 8 minutes until glossy and slightly thickened.
Season to taste, strain if you like a smooth gravy and serve hot.