Hi Tiki,
I too am trying to trace the origins of my Great Great Grandfather, George Thomas, who came to NZ with one of the Imperial Regiments about 1860ish. All I know is that he was born in about 1826, was possibly Irish, and could have been in either the 65th, 70th, 18th or 57th Regiments (each one had a George Thomas). He settled in Auckland NZ and later married Delia Shanaghan sometime between 1864 and 1872. Their son, also a George Thomas, was my Great Grandfather.
Do you think we're looking for the same person?
Cheers,
Grant