Re: Huawei
Slavery wasn’t finally abolished in Britain until 1838. Slavery wasn’t abolished in East India Company territory, Ceylon and St Helena until the Indian Slavery Act 1843. That’s close enough to “mid-19th century” for me.
For that matter, Bentham gave no indication that his theory of natural rights applied only to Britain and the Colonies. He was speaking in generalities, so generalities about the state of the world at the time apply.