there were some african slaves on the Island (eg grave of Samuel Alley in Braddan)- many free or run-away slaves also served on mechant ships and there was a large black community in Liverpool - John Brown who founded the IoM Times was of mixed blood from within this community - slaves were legally free if they reached Britain (where slavery was illegal)- there is a comment in a letter by John Collet(orig Corlet) who settled in New York of 1788 who describes taking a certain 'black Mark' with him on a voyage to Amsterdam where black Mark ran off and joined the Dutch East India Comapny (mind you he had suffered a hard + bold vovage and been frost bitten en route so no doubt was looking for warmer climes!)