 He probably met his future business partners Anthony Calvert (1735–1809) and William Camden at this time when he was master on ships owned by them.He first partnered with them as Camden, Calvert and King for the voyage of the "Three Good Friends" to St Vincent in 1773 and the firm subsequently made many slaving and trading voyages in which they transported at least 22,000 enslaved persons, mostly from West Africa to the Caribbean.In 1776 he was tried for murder at the Old Bailey in London but acquitted.