Eventually found the correct, John PERCY, in New Zealand - and whilst he continued for a time in education, he'd also taken on another occupation ... and moved to another province (Nelson).
[Have yet to find anything for his wife Hannah. ]
From around 1858, there were newspaper birth announcements .. and very sadly, a number of deaths of children of Mr J PERCY (or Mr John PERCY). I found the following burials at Fairfield Cemetery, Nelson :
1854 - Emily Howick PERCY - d. 30 March 1854 - aged 5 months
1858 - John James PERCY - aged 3 years, 8 months (possibly named for a brother ?) d. 27 December 1858.
1863 - Ellen Kate PERCY - d. 11 February - aged 8 months.
1868 - Ernest Noble PERCY - d. 18 October - aged 10 years.
All these burial records marked "child of Mr J PERCY".
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Can't see a family tree for this man, so it may well be that no children survived him ??
Additionally, there was a death notice published in a Nelson newspaper at the same time (1868) as son Ernest, passed away, recording the death of "Mrs Anne PERCY (on 1 June) at Howick, Northumberland, (ENG), the mother of Mr J PERCY of this city."