If it isn't the oldest, it certainly must be ONE OF the oldest ones. They weren't making them for very long before that, and not so many of the ones that were made would have survived, especially if you require them to be working today!
That said, I always think it's possible there are some tucked away somewhere, forgotten. Think of the extraordinary things they find every few years in Great Manor Houses. People who lived in them could afford these kinds of toys, and had room to set them aside in some closet or unused room where they could still be sitting, unappreciated and ignored by their current owner ... who might never have heard of the contest, or bothered to contact anyone. There probably is an older set somewhere (probably NOT working)... but finding out WHERE it is, would be a challenge, for certain.