Well, given that fuel is dispensed in litres, but distances are measured in miles, wine is measured in ml and beer in pints, the systems we tend to use are somewhat fluid.
Pint isn't an official measurement (officially its 568ml) but it's popular in colloquial usage, you buy a pint of beer, but not a pint of milk or motor oil. Ordering a pint is just something that's ingrained in UK culture (and most commonwealth countries) and not going to change any time soon.
Height is a good example, when talking about height we use feet and inches but on any official document it's measured in centimetres.
Australia fully converted to metric before I was born, but old imperial measurements are still popular in conversation.