Did a little searching for investors in the Darien Company. So far no
SInclair or Scott family connections. A book by Don Byrnes called "The
Blackheath Connection" (all on the net) has a lot about the  Darien Co. The
power behind it was largely the Campbells, starting with Neil Campbell,
president of Glasgow University. There were investments from Glasgow
merchants, but no mention in what I read tying our family in. If we had
complete records, we could find something interesting. Other investors
included noble families of Argile, Patersons, and Erskins. These may have
connections with the Caithness nobles with similar names. Maybe your
researcher will pick up something with records of this project.