The slave trade generated finance. It was an essential source of tax revenue. West Indian colonies were a source of valuable exports to European neighbours.
Abolition would mean taxes would have to be raised to compensate for the loss of trade and revenue. It would also help foreign rivals, such as France, fill the gap left by Britain.
Individuals, businesses and ports in Britain prospered on the back of the slave trade. British cotton mills depended on cheap slave-produced cotton. Africa provided an additional market for British manufactured goods.
Shipbuilding benefited as did maritime employment. It was argued the slave trade was vital so that Britain was able to sustain an expensive war effort against France.