In manufacturing, the UK has been completely metricated for donkey's years; the construction industry, likewise.
Aside from the use of miles on road signs (judged to be far too expensive to change), the use of MPG for fuel consumption (but not compatible with US MPG as the US gallon is much smaller than the UK gallon), the use of pint measures in pubs (but millilitres for spirit measures) and the continuing use of square feet and acres by estate agents, just about everything in the UK is fully metricated. However, in the personal field, I think most people still talk of their weight in stones and lbs but doctors use Kilos. Likewise with height, the public tend to use ft & inches but medicine uses centimetres.
Talking of metrication - when were you last prescribed a medicine in grains, scruples or fractions of an ounce? Even in prehistoric America, the pharmaceutical industry has been metricated for a very, very long time!
@Paulos_the_fog And milk, food, peoples weights... Sounds like you guys are still on imperial outside of engineering or technical pursuits more or less. When I was in UK last virtual everything Im exposed to day to day was imperial.
Not food - you are obliged by law to price and sell that in metric units in the UK - for milk likewise it may be a UK pint, but the the labelling has to be in millilitres. To me what the US does is utter insanity but thankfully it doesn't really impact me!
One of Britain's largest industries is the construction industry and that is 100% metricated (I would know - it's the industry I used to work in before I retrained as a software engineer).
@Paulos_the_fog I'd argue using two separate systems interchangeably is **far** more an insanity than having a purely imperial or metric system.
1) Yes there is an imperial system just as much as there is a metric system (https://en.wikipedia.org/wiki/Imperial_units)
2) Yes most countries that Officially and/or primarily uses the imperial system will also sometimes use units outside the imperial system, sometimes that will be metric
3) While I wouldnt say "professionals" in the UK exclusively use metric I think its fair to say scientists and engineers do at least. However describing what system or units a country uses is not limited to what their scientists use, and the fact is, as a country, they use a horrid mess of imperial, metric, and in some cases nonsense that is neither (stones instead of lbs). Far worse than the mess int he USA, at least they are consistent and use one clearly defined system.