This is all consistent with the fares here: http://www.hardlink.com/~markdu/OWFi...orerFares.html

N America DONEn fares are roughly double the price of LONEn and AONEn is roughly three times, whereas in the UK, DONEn is roughly three times the price of LHONEn and AONEn is 4-5 times more than LHONEn.

(Meaning that business class is very roughly the same in both markets, economy is significantly cheaper in the UK, and First is significantly cheaper in N America.)