He met with William Pitt the Younger, the Prime Minister, on several occasions and with William Wilberforce in 1783 and played a significant part in the establishment of the campaign against the slave trade. It was his meeting with Thomas Clarkson in 1786 which encouraged the latter in his tireless efforts to obtain first hand evidence of the trade, and indirectly led to the formation of the Committee for Abolition of the African Slave Trade the following year.