Many merchants and shipowners made their fortunes to do with Slavery, but despite the fact these people linked to slavery the slaves did not come to this country from Africa.
What happened was trade goods were taken from Bristol, Liverpool and other ports to Africa, there they bargained with the chieftains who looked on their own people and those of other tribes they stole as trade goods. The ships then sailed the Slavery triangle to the West Indies and USA. the ships then came back to UK loaded with cotton, sugar and rum.