Hi George,
I saw your message and just want to say,welcome to Wikitree,I am relatively new to Wikitree( maybe 3 mothts) and so far I enjoy it a great deal.Unfortunately,other than our rhyming surnames,I do not have any input to offer on William Robson-from what you know so far do you know where he lived? Many of my ancestors were migrating as slaveowners,missionaries or unwillingly being brought across the Atlantic as slaves to the then English colony,Jamaica at approximatelly 1800-1830 or so.
Best of luck in discovering family stuff,I find that months go by with no breakthough finds,then one or more appear.
(George Winchester)Mark Jobson