Ugh. My wife grew up in England, and puts malt vinegar on her fries. Disgusting. Makes its completely not worth it to steal her fries after she does that.
I met French Fries dipped in mayo in London..I asked for ketchup..the waitress laughed and told me their ketchup wasn’t as good as ours. LOL
Maybe your final sentence contains the answer as to why she still puts malt vinegar on her fries, even after leaving England...