@bigcathead he’s only been in England for like two years at most (I don’t actually recall exactly when Sebastian is supposed to have entered Ciel’s employ and then found the other servants), it’s more likely a case of the anime dub not realising that he, Finny, and Mey-Rin are all foreign and OP making the same mistake. He doesn’t hide that he’s American so there’s no reason for his accent to have changed - he may have picked up mannerisms from those he spends the most time with, but that wouldn’t be enough to erase his accent unless he was actively trying to. And the people he speaks to most are the other servants. In that house only Sebastian and Ciel would have an English accent, and neither would be cockney because Ciel is upper class and butlers had to be as eloquent as possible - both would speak received pronunciation “Queen’s English”
And while Finny and Mey-Rin both got English lessons from Sebastian (and Finny, being young, is most likely to have his accent change naturally), Bard didn’t. It’s in the manga~
