Who were Samuel LINTERN and Hannah GIBBONS?

Neither Samuel nor Hannah can be found in ships' passenger lists and no newspaper archives exist for Samuel before 1867.  Did they arrive separately or come out as a couple?  Their New Zealand 'Intention to Marry' document states 25 year-old Samuel to have been resident for six months, and 22 year-old Hannah for twelve months, both of Oamaru (this points to her being born circa 1845).

There was an Anne Mary Gibbons christened on 28 July 1847 at St Andrew by the Wardrobe, London, England, daughter of Sills John & Ann Gibbons (nee Crookes).  Our family bible has Hannah's details entered as "Hannah Mary" born 24 June 1847, which fits in with the above christening entry.  If this is correct, then she was aged 20 upon marriage, not 22 as stated on the 'Intention to Marry' document and would have been a minor requiring parental permission to marry (they were married by special licence).  According to the marriage certificate, she was a spinster of full age (over 21).

Where would the informant (the undertaker) on Hannah's death certificate have gotten Hannah's alleged mother's maiden name of CROOKES?  Even if Hannah had fancied having a one-time Lord Mayor of London as her father and 'taken' the name Ann Mary Gibbons, how would she have known Ann Gibbons' maiden name, unless she was family?

On Samuel's probate document, Hannah is named as Ann.

This is the couple frustrating the heck out of me.  Would love some help with this one!