The conjectural account of Ignatius Sancho's earliest years offered by Prof Brycchan Carey in his talk for the Equiano Society is extremely plausible and answers one puzzle, that presented by his name. while Equiano through and after his years of enslavement acquired several names, as was common for such displaced individuals, Sancho appears to have had only one from the age of around two years - and one that did not change when he was domiciled in Britain - where Ignatius was an unusual appellation.
Enslaved people - boys especially - were often mocked by being given classical names such as Pompey, Caesar, Hector, presumably as a kind of joke, underscoring their utterly powerless status with a heroic comparison. Ignatius wouldn't work in quite the same way. In Britain it was a Papist name, from Ignatius Loyola, founder of the hated Jesuit order which in the early 18th century was still popularly believed to plot to 'return' Britain to Catholicism. Attached to a friendless African orphan, it also would have a mocking element, which might explain why it was not changed to a more easily pronounceable name for a household servant.
In the preface to the Letters of the Late Ignatius Sancho, an African, it is stated that Sancho was 'born A. D. 1729, on board a ship in the Slave-trade, a few days after it had quitted the coast of Guinea for the Spanish West-Indies, and, at Carthagena, he received from the hand of the Bishop, Baptism, and the name of Ignatius.
Starting here, Brycchan Carey posits that the boy was in a shipment of captives landed at the slave entrepot of Carthagena [now in Colombia] where the Jesuit order ran the church and organised mass baptism for Africans, in a cathedral dedicated to Loyola. Hence his 'Christian name'.
Thence he was transported to Cadiz in Spain, another great trading city, where ships of the British Navy were then able to anchor, and where he was acquired or bought by a young naval officer. [If the dates are right, he seems a bit young - under three - for this, but maybe it was comparable to acquiring a puppy] The midshipman was related to sisters living in Greenwich (conjecturally identified as Elizabeth, Susanna and Barbara Legge) to whom on his return to Britain it is suggested young Ignatius was presented as a gift According to the Letters preface, these women ' surnamed him Sancho, from a fancied resemblance to the 'Squire of Don Quixote.' A fanciful name for a black servant who had apparently come from Spain.