Put the flour in a saucepan and place over a medium heat. Toast the flour by stirring every few minutes so it doesn't burn for about 15-20 minutes until it's lightly golden.
Add the butter and stir together. Pour in the wine, a little at a time, whisking as you go to avoid lumps, until it's incorporated.
Add the stock cube/pot, water and some salt and pepper. Return to the heat, reduce it to medium-low and cook, stirring occasionally, for 40-50 minutes until the winey taste has gone. It should be nice and thick.
Pour in all the juices from the roasting tray and any resting juices from whatever roast you have made. Whisk together, check seasoning and serve.
