“Very little is known about the life of Dido Belle, who was born in the West Indies and was the illegitimate mixed-race daughter of Mansfield's nephew, Sir John Lindsay . She is found living in poverty by her father and entrusted to the care of Mansfield and his wife.
“The fictionalized story centers on Dido's relationship with an aspiring lawyer; it is set at a time of legal significance, as a court case is heard on what became known as the Zong massacre , when slaves were thrown overboard from a slave ship and the owner filed with his insurance company for the losses. Lord Mansfield ruled on this case in England's Court of King's Bench in 1786, in a decision seen to contribute to the Slave Trade Act 1807 .” - more at Wikipedia