Originally Posted by
pbarnette
Not quite true with regards to BA. From the BA website:
Silver membership can also be earned or renewed when you take 50 one-way flights or 25 return flights with British Airways.
Gold is strictly via Tier Points, I think. Haven't looked into it, but I believe that these can be in any fare class. Not a great deal, surely, but it is a recent change of note.
Worth remembering that BA Silver is
oneworld sapphire which is similar in benefits to ST E+ and *Gold. (i.e. business class lounge access, business class check-in, etc). BA Gold gets you first class lounge access and check-in which no ST tier gets you.
There's no BA tier that corresponds to oneworld ruby which is equivalent to *S or ST Elite.