The “sauce marchand de vin” is a French red wine thick sauce typically served with meat. Its recipe in my French cookbooks call for two main ingredients: red wine and brown stock. It also uses shallots, butter, flour and black pepper, but I understand the two ingredients cited previously are the main ones.
However, many recipes I can find online (here and there, for example) on English-speaking websites add Worcestershire sauce. Not all of them do, but I still wonder: what purpose does this extra Worcestershire sauce add? I'm not too familiar with it, but if I understand it might bring some spiciness (already somewhat covered by black pepper).
So, what do you think it brings to the recipe and overall taste?