It is, indeed, a matter of age, Tony. I function "adequately" in the metric environment but was taught imperial measurements at school. Even now I often have to convert a metric measurement to imperial to get a sense of scale. For example, a metre is a couple of inches over a yard.
Having said this I think that now we are all at least accustomed to metric measurements and know either how to convert or know where to go to find out we should stay with them.
I'm not sure where I'd go, though, to find the value of a groat, though.
Brian