Brown the carcases, giblets and trimmings in the oil in a saucepan for 10 minutes. Add the carrot and onion and brown them lightly. Then add the red wine and the demi-glace.
Bring to the boil and simmer very gently for 3 hours, skimming frequently and adding cold water to maintain the level of liquid. You should end up with 1 litre (1¾ pints) stock.