Most Imperial units are not British

One of the myths about Imperial units is that Imperial units are made in Britain. The truth is very different, although Imperial units were defined in the 1824 Weights and Measures Act which made several other traditional units obsolete, the origins of Imperial units, which came from medieval English units of measurement, are not British. 

Imperial units were mostly brought to Britain by the Romans almost 2000 years ago, other units were introduced by the Angles and Saxons from Northern Germany who brought their own measures, the Normans reintroduced Roman style measures, and others were later adopted and modified from medieval French variations of Roman units, known as avoirdupois and troy measures.