Lord Dumfries began to seriously extract coal in Cumnock in the last four decades of the eighteenth century. Relatively few worked in the mines in the early years and even by the end of the century there were only a couple of dozen colliers in Cumnock. Here are the names of the coal miners in Cumnock in the records of 1767-68.
Many of the coal managers and operators in Scotland at this time were English. This might explain the unusual spelling of some of the surnames in this account (eg "Grime" and "Grame" for "Graham"). In 18th century Cumnock, "McCowan" was such a more common name than "Cowan" that it is very likely that "James Cowan" was actually James McCowan. It is possible that this was the grandfather of James McCowan of Scarborough.
The Scarboro Heights Record V11 #3