Mick,
If your relationship with Jane is direct along your maternal line then an MtDNA test would indicate you have Aboriginal DNA. MtDNA is inherited through the maternal line.
e.g. Jane Baker > her daughter > her grand daughter > her great grand daughter > her great great grandson (YOU).
If, however, any of her maternal ancestors were white then she would not have passed on Aboriginal MtDNA to you.
Rosemary