I qualified for Silver rather randomly when I had 3 oneway CE+CW flights between mainland Europe and JFK/EWR (via LHR) during one year. Basically I used to flew BA once a year on holiday (+ some random VIE-LHR travel in WT*) - my membership year ends in August, holiday in 2010 was entirely in August (begining of membership year 2011/2012), holiday in 2011 had outbound flight in July so I qualified for Silver for 2011/2012. I would qualify again if I timed my this year's holiday right, but we postponed it for fall or winter.

Anyway, I used my Silver card on 4 flights only (1x FRA-LCY, 1x LGW-AMS and 1x VIE-LHR-VIE). Since my "main" airline (HG) is now part of oneworld I would use benefits more if I qualified again. But I didn't. Which is pity because OW lounges are usually more than great (I would actually be willing to pay for them), but honestly - I don't deserve that status.

* I'm on that route 2-3 times a year, but usually on easyJet since they fly to Gatwick which suits me more