I was browsing some UK sites recently and I remember one of them saying something about import duties. I don't think it was End either. Hope I don't get the same when my Universal Works coat comes this week. That's coming via Royal Airmail though, so maybe I won't have to pay it.
One of the sites I was looking at did deduct the 20%, but it was tough to see. When you changed the currency to USD the value was 20% less than it was in British pounds. I used a currency converter to check it.
I checked it and I think you're right.