I have gas fired and it is ornamental. Wood burning is great and produced wonderful heat. A dry heat. but still great and when heating oil is at an all time high, wood burning cna save you lots of $$

since most of the metric conversion films and educational bits I grew up watching in school in the mid 70s (when America was *supposed* to switch to metrics) were British, I'm going to say the UK switched in the late 60's to early '70s.

the US began putting both measurements on packaging in 1971 and full compliance was supposed to be complete by 1974 with the English measurements gone. It never happened. the English measurements stayed along w/ the metric measurements.

I would guess the UK did their switch either just before or at roughly the same time as the US was attempting to make their change.

edit:
according to this site: Britain voted in 1965 to go metric in 10 years' time. Their big push to convert was in the 1970s.
http://lamar.colostate.edu/~hillger/internat.htm