No takers?. OK I'll put forward my theory.
His Grand Dam is Eight Carat, so a link to diamonds there.
Lonrho is a London based company that owns & operates diamond mines in Zimbabwe, formally Rhodesia. The name is made up of LONdon/RHOdesia. So if Lonhro is named after this company then his name has been spelt incorrectly. That's if. It's possible as the Ingham horse are usually well named.

Makr.