Hi Bettyanne
Mary Jane Hall was married to my great great grandfather, Thomas Wright, I guess sometime in the early to mid 1850s - I have no record of the marriage, but they had four children, including my great grandfather, William Wright, born in Quebec in 1859, and a sister born in Bermuda in 1861, both when the 39th Foot was posted to those places. In the 1871 UK census Mary Jane is shown as widowed and living with nephews James and William Hall, children I think of John Hall, the 39th Drum Major. They are also living with Mary Jane's mother, Elizabeth Murphy, born in Castlebar, Ireland.
Looking at the Australian birth index I found a Mary Jane Hall, born to James Hall and Elizabeth ? in 1831 (my Mary Jane's birth year and birth place) and entries for John H Hall born in 1830 and a Sarah J Hall born in 1836 - all born in New South Wales and registered in Sydney.
Not all of this is conclusive, but I think that my Mary Jane and your John Hall were born in Australia of an Irish mother, Elizabeth, and I guess that as John Hall and Thomas Wright were in the 39th, my g g grandfather met his wife, Mary Jane, through her brother. I don't yet know anything about James Hall, or how Elizabeth came to be in Australia with James Hall. I also don't know the significance of Elizabeth's surname Murphy in the 1871 census - perhaps she married again, or perhaps it was her maiden name.
Rather a lot of guesswork, I'm afraid, but I hope some of this strikes a chord. I'd be grateful if you would let me know if you have anything to add