Looking for Campbell- Johnsons of Jamaica.

Robert Alexander Campbell-Johnson came to Australia late 19th century and married an Australian nurse called Agnes - the 5 children were George, Elenore (Nellie) and 3 others. George was my grandfather.

I believe there was something to do with the Jubliee Plantation which I understand is now a hospital.

Robert Alexander Campbell -Johnson was one of 2 brothers - the other brother went to Toronto, Canada.

The family name was Welesly which was the second name of all my cousins.

Can anyone fill in the gaps for me?

My grandfather always referred to "Spanish" ancestors but I believe that the ancestory was African.

Would love to hear from anyone with information.
With many thanks
Kathryn