A hot or cold pouring sauce based on redcurrant jelly, Worcester sauce, red wine, mustard and lemon, thickened with either flour or minced onion. Known only since the 1960's and in J.Salmon.

Original Receipt adapted from from D.Smith at www.deliaonline.com

Shrewsbury Sauce
[meat fat and juices]
2 level tablespoons plain flour
1 heaped teaspoon mustard powder
1 pint (570 ml) Beaujolais or other light red wine
5 rounded tablespoons good-quality redcurrant jelly
3 tablespoons Worcestershire sauce
juice 1 lemon
salt and freshly milled black pepper

To make the sauce, spoon off any surplus fat from the roasting tin, tipping it to one side and allowing the fat to separate from the juices; you need to leave about 2 tablespoons of fat behind.
Now place the tin over a direct heat turned to low and stir in the flour and mustard powder until you have a smooth paste that has soaked up all the fat and juices. Next, add the wine, a little at a time, mixing with a wooden spoon after each addition. Halfway through, switch from the spoon to a whisk and continue to whisk until all the wine has been incorporated.
Now simply add the redcurrant jelly, Worcestershire sauce, lemon juice and seasoning, then whisk again until the jelly has dissolved. Now turn the heat to its lowest setting and let the sauce gently bubble and reduce for about 15 minutes, then pour it into a warm serving jug.