On his return he settled in Bristol where he began a business partnership as a sugar merchant with
James Tobin, the pro-slave trade campaigner. They owned ships trading between the West Indies and England, loaned money to plantation owners on which they charged interest (from which he made most of his wealth), and took over plantations and slaves from those who could not pay their debts. During his time back in England Pinney increased his wealth 5 times from that which he brought back from Nevis. When he died in 1818 his fortune was worth about £340,000 (the equivalent of about £24.5 million as of 2019, based on the percentage increase in the Retail Price Index from 1818 to 2019). and Pinney’s manservant Pero Jones (1753–1798) who was never freed.
Pero's Bridge in Bristol is named after him. Unusually, Pinney was not a member of the
Society of Merchant Venturers, but was a member of the West India Association in Bristol which in the late 1780s lobbied to defend the slave trade. His son
Charles Pinney took over much of his father’s business, although John Pretor Pinney's main estate of Mountravers had been sold in 1808. ==Death and legacy==