From a portrait by Thomas George, lithographed by Richard James Lane 
(formally one of Charles Heath's pupils) in December 1833. 

The title at the bottom reads:
James Heath
Historical Engraver to George 3rd, George 4th, William 4th
And Associate of the Royal Academy 

The whereabouts of the original portrait is unknown.
If anyone has seen it I would be very pleased to hear from you.

(James Heath)