I used to live in New York. This was a good idea, and a bad one, as most ideas are. The problem with New York is, there is so much there, a person can forget What Else Is Out There In The World. Fortunately, I failed as a New Yorker, and got to see something of What Else Is Out There In The World.
I have not based Jacob Marley on a historical figure. I was inspired by a photograph I took in New York, on Great Jones Street, of a weathered stone architectural detail. I think the street address is 43 Great Jones. I have always thought of it as the Ghost of Jean-Michel Basquiat, who had a studio at the end of the block at number 57. I always thought that the weathered face should have some kind of ornament fixed on it, or a crown.
So, anyway, I made a sketch from my photograph and built up Jacob Marley's features from the proportions in the stone, and expanded upon the surrounding scrollwork to form the door-knocker, where Marley's Ghost first appears to Scrooge.