Hi Sue,
Just a note to let you know that you were correct in guessing that John Francis CHRISTIAN might have arrived in Otago during the Gold Rush years.
His grandson (David Christian) has a very good picture of his early years here. Thinks he arrived initially abt. 1861, he would have been only 20yrs old.
He was a miner from that time, until almost the year of his death, 1920.

John (of Kyeburn Diggings) and Eliza Mary COWIN (single) of Isle of Man, were both passengers on the "SS Tainui" which left Plymouth June 1885 - via Hobart, arriving Port Chalmers 2 Aug 1885. They were married 9 weeks later.
I'm sure that there will be a lot more questions still to come regarding the IoM connections!
Many Thanks,
Regards,
MC