[2] He was a vice-president of the London Institution and leader of a group of merchants and speculators who, in a private venture, undertook the construction of the docks at Wapping.
The London Docks Company had a 21-year monopoly to unload all vessels entering the port with tobacco, rice, wine and brandy (except from the East and West Indies).
Long and the other directors sat in the London Dock House, in New Bank Buildings, from where they oversaw their involvement in the transatlantic slave trade.
[4] In June 2020 the Bank of England issued a public apology for the involvement of Long, amongst other employees, in the slave trade following the investigation by the Centre for the Study of the Legacies of British Slave-ownership at UCL.
Long married in 1786 Frances Louisa, eldest daughter of Sir Richard Neave, 1st Baronet.