Except the UK has never gone 'properly' metric. They still teach the kids a hybrid mix in schools, speed limits and distance signs still use miles and most people still do heights and weights in imperial. I'm surprised after Brexit we haven't all had our minds wiped to get rid of the nasty metric stuff!
As a scientist I switch kind of automatically in my head but there's always the odd cock up. Best I remember was the Mars probe that suffered a rather hard landing due to an error in conversion. Bet someone got a new calculator after that one!