A fifty year rule would…
mean that the Mark 11 would barely qualify (and not qualify if you consider the civilian version available into the early eighties) and that the classic Ingenieurs, like the reference 666, would not qualify either.
"Antique", in furniture and others, is usually given a one hundred year threshold. Where does that zone exist of vintage but not yet antique?
Clearly something still in production, even if it has been in production for decades, is not yet vintage. So how long does it have to have been out of production? I confess I don't have a clear answer.