As the illegal slave trade to Brazil continued to expand throughout the late forties in the absence of any really effective preventive action by the Brazilian authorities and in defiance of the most extreme measures so far adopted against it by the British navy, opposition in England to what John Bright called Lord Palmerston's ‘benevolent crotchet for patrolling the coasts of Africa and Brazil’ gathered considerable momentum both inside and outside Parliament. It was towards the end of the previous decade that a degree of dissatisfaction with Britain's traditional anti-slave trade policies had first become apparent. Considerably strengthened and extended the British preventive system had nevertheless been given a further period in which to prove itself. If, however, its raison d'être was the suppression of the illegal transatlantic slave trade, or at the very least a substantial reduction of it, with the Cuban trade as well as the Brazilian still flourishing its failure could no longer be denied and there was evidence of a growing conviction that it ought now therefore to be dismantled.

Since its foundation in 1839 the British and Foreign Anti-Slavery Society, very much Quaker dominated, had been opposed to the use of armed force for the suppression of the slave trade and, consequently, completely out of sympathy with the anti-slave trade efforts of successive British governments, both Whig and Tory.