Good find Lu - I hadn't found that NZ Gazette.
I have pursued uncle James Whelan - his 1857 Irish Police Service record, and his 1861 Marriage Cert (to Honorah Fitzgibbon) in Victoria, both state he was a native of Queens County, Ireland.
Charles Whelan's 1923 Death Cert (provided to me by another researcher) was a Certificate (unfortunately not the printout), but it does give his place of birth was Galway, Ireland; and gives his father as Unknown, & his mother as Ann, m.s. Unknown.
On re-reading that Wikipedia article on Voting rights, I think the author could have worded it better. A reader could be excused for interpreting it to mean that the only eligibility requirement for the special Goldfields Electorate was the presentation of a mining right. The base prerequisites were set out in the Miners' Representation Act 1862 - the need to be a man, to aged 21 years or over, to be the holder of a Miners Right, and to have resided in the relevant Province. The special Goldfields Electorates relaxed those prerequisites by removing the residence requirement. The gender and age requirements still applied.
Charles Whelan could of course have lied about his age, but I think that is unlikely knowing what we do about him. His whole life was committed to compliance with rules and regulations, I can't see him breaking the law in order to gain a vote.
Lu, at one stage you expressed some exasperation that I hadn't given Charles Whelan's full name from the outset, but in my defence I was really only giving some context for my principal query - I was hoping someone would direct me to where in NZ I might sight the Electoral Roll which FamilySearch microfilmed. Unfortunately that query has not yet been resolved.