BA's newer Boeing a/c such as 747-400s don't have them (it's apparently an airline-specified option) while 747-200s (now all retired) did.
I think all Airbuses that I've been on (NW, US, CP) do have them but I understand various AC a/c don't.
NW DC-10s don't have them at least for 1A. The vents used to be mounted in seat backs when the DC-10s first came into service.