Hi Sue,
Mark Kelly and Mary Jane Batt were my 3rd Great Grandparents. Mary Jane was half Aboriginal, and Ancestry DNA records indicate her father (George Batt) as having been English. Back in those days State Records usually addressed white Australians as English or British persons.
Mark, on the other hand, was not Aboriginal, in most records, he is referred to as Irish or European and that his birth year was 1859/1860. I've yet to find out whether or not he was born in Australia, Ireland or the UK. Birth records of Mary Jane are accessible online, for example, she was born in Minilya Station and grew up around Sandstone. But trying to find any birth information on Mark is terribly tricky.
The best I've managed to find is an 1864 Empress of the Seas passenger list outlining that a 5-Year-Old named Mark Kelly came to Australia as an assisted passenger. The ship had travelled from Liverpool to Melbourne. But confirming whether or not this is our ancestor is tough as Mark Kelly is an incredibly common and generic name. Not to mention, he was not the only Irish/European Mark Kelly born around 1859 to end up in Australia... Furthermore, back in those days, it was common practice for Britain to send orphans or foster children to Australia. Many of these children ended up being placed in the Missions with Aboriginal children. This might explain how Mark came to meet Mary Jane, although, this is just me speculating with the little information I've been able to find.
I should also mention that Mark Kelly was Mary Jane Batt's second husband, her first husband's name was Joe Lennie, and he was Aboriginal. So whoever told you that Mark was Aboriginal just got their husbands mixed up.
Anyway, during the 1890s, Mark Kelly lived and worked on the Goldfields at Bangemall Hall. There's actually an 1898 West Australian article about Bangemall Hall that you can view online via Trove. This one, in particular, explains how Mark had almost been burned to death when his bough hut caught fire while he slept. Luckily, he had been rescued by a friend. Furthermore, the family had lived around the Gascoyne and Murchison regions until their children and children's children ended up further down south, in or around Perth. This was due to them having been placed in the Moore River Settlement, and later, Roeland's Mission. Other areas include Wagin and Pinjarra, but there are still some Kelly's who live closer to the top end of West Australia.
And to finish off this long reply, you mentioned that Angelina Brand was your Great Grandmother? Her birth name was Angelina Rose Kelly and her brother, Charles Brackell Kelly, was my 2nd Great Grandfather.
I hope that what I've written has been of some help to you
All the best,
Jocelyn.