A good point about Margaret's age. I wouldn't be surprised though (from family stories) that one or both of them were locked up prior to the marriage. But it is also quite possible that one or the other were married before as well.
I am indeed researching the marriage to find out the origins of John Edward DUNNE & Margaret KELLY. I have 4 birth certs, for Annie, Rose Ellen, David James & Catherine.
For Annies cert 1878 Leyburn QLD, John Edward DUNNE was the informant. He stated he was a miner, 45yo, and born in Monaghan, Monaghan, Ireland.
For Rose Ellen's 1882 Inverell NSW, J E DUNNE was the informant. He again stated he was a miner, now 52 yo, and born in Ireland.
For David James 1886 Inverell NSW, John Edward DUNN was the informant. He stated he was a miner, now 56yo, and born in Ireland.
For Catherine 1893 Crocodile Creek QLD, John Edward DUNNE was the informant. He stated he was a miner, now 67yo, and born in Monaha, Ireland. There were 7 other children still living, and 1 male deceased at her birth.
Margaret KELLY was alive in Sydney in 1909 at daughter Catherine's marriage. John Edward DUNNE had passed away by then. I have been unable to find either John's or Margaret's death record as yet from searches in QLD & NSW.