There has been some debate in Tasmania about whether this portrait is actually that of "Dolly" Johnson. Those who hold the original strongly believe it is. Others, using scientific and historical analysis, strongly doubt this.
If it is not a portrait of Dolly Johnson, it is possibly that of the second wife of Thomas Johnson the Elder. She was born Pauline Bourne. Another possibility is the wife of Thomas Johnson, son of Thomas the Elder and "Dolly". She was born Elizabeth Atkinson.
At this point I don't have sufficient evidence to be sure either way. If you have any information which might clarify the source and/or accuracy of the image, please email me.
Mannalargenna is Dolly's grandfather. He was Chief of the Cape Portland Tribe
Descendant Tree of Mannalargenna
Family History Report for Mannalargenna
Outline Descendant Tree of Mannalargenna