A lot of the English words we use are essentially loanwords due to the Norman Conquest of England nearly 1000 years ago. The Normans spoke their own variation of Old French. From Middle English to Late Modern English (what we speak), the language has been bastardised.
Incidentally, the English Imperial system is French. It used to be called "avoirdupois". We adopted the system in England in the 1300s.
From the mid 1960s, a lot of UK schools adopted the metric system, even though we still retain some imperial mesaurements for height, weight and mileage. As part of the EU, we're expected to use metric for business goods - which could change if we vote for Brexit.