The earths on lighting circuits here in Ireland wern't manditory until relatively recently, I'm not 100% sure when they came into force. However, this house was originally wired in 1971 and has none! We had a horrible retrofitting job, particuarly down stairs where there was no access from behind the ceilings. Only a couple of old metal fittings upstairs and the bathroom lights were earthed.
I think the logic in the old days was that people would be quite happy with plastic fittings and if you wanted a metal fitting it would be installed by an electrician anyway, thus properly earthed. They didn't seem to count on the DIY jobs done everywhere.
There are certainly plenty of metal light fittings around that arn't earthed.
More worrying is when people install brass / metal switch plates in 1960s/70s wired houses and don't bother hooking up an earth.
