[Paal Gulli]

"The British eradicated slavery....

Or so they claim, but at least three British territories still had slavery into the 20th Century (British East Africa, Tanzania & Hong Kong).

There also was slavery in German Tanganyika when the Paris Peace Conference ceded the territory to Britain in 1919, but that was none of the Brit's fault.

[Reily]

So deeply ingrained in those local cultures the Brits didn’t have the manpower to enforce it even they wanted to! Best that could be done is try and contain it.