The britons had already been strangling the slave-trade, and just about all european nations had already abolished slavery itself, or were under severe pressure to do so. As had many (but not all) latin-american countries.
(Cuba and Brazil being the major exceptions)
The brits (and to a lesser degree the french) were doing everything they could to make slave-trading annoying and expensive (with some success) not the least because "stopping slavery" was a really handy excuse to intervene in the internal affairs of various african states.