~~~ members and their guests knew about it.

If this was not a gift from someone very important in Portugal, in the casino industry, I would discount the information. My feeling is that there are too few collectors in Portugal, not only now, but 50 or 60 years ago, who would have caught something like this or personally knew a member or the son or daughter of a member. In all my years of collecting, and doing business with all the casino owners and group operators I have been in contact with, I found their information to be quite accurate... and I have no reason to doubt them... We may never know where exactly the club was, but I trust the information I received in all cases was correct. Maybe one day we will find some information.