When the ship returned home the insurers disputed the captain’s claim. The owners therefore brought a suit against the insurers, demanding to be paid £30 for each slave, and were backed in King’s Bench; the underwriters then petitioned the Court of the Exchequer. Lord Mansfield remarked that the jury had to decide whether the slaves were thrown overboard from necessity
‘for they had no doubt (though it shocks one very much) that the case of slaves was the same as if horses had been thrown overboard)'.By this time Collingwood was dead. The barrister for the owners argued that
‘So far from the charge of murder lying against these people, there is not the least imputation - of cruelty. I will not say - but [even] of impropriety’.However the abolitionist Granville Sharp tried to take the case to the Court of Admiralty but failed. The Solicitor-General, John Lee, deplored his ‘pretended appeal to humanity’, and declared that a master could drown slaves without ‘a surmise of impropriety’.
But public opinion was turning. Sharp now had the support of most of the bishops, most notably Beilby Porteus, bishop of Chester.
In 1783 a bill was introduced into the Commons forbidding officials of the Royal African Company from selling slaves and the Quakers petitioned parliament for a general prohibition of the slave trade. Lord North, then Home Secretary, said it was impossible to abolish the trade, since it was ‘necessary to every country in Europe’. But 1783 was the last year in which the Liverpool Quaker timber firm of Rathbone and Son supplied timber for the African trade. Even in Liverpool, therefore, opposition was building up.