It's simple. Golden Cup was made by Mackintoshes (as was Toffee Crisp and Rolo). If i remember rightly, Mackintoshes was bought out by Rowntrees, who in turn became Nestle.
Nestle own the brand names, even if they don't actually still make the product. They probably kept the brand name for use in the future. As an alternative, they might still sell Golden Cup aborad, say in South Africa or somewhere.
One thing you can be sure of. If the bar is still made, it won't taste anything like the original. Just think of Toffee Crisp and the cheap chocolate that now covers it!
