Whilst trying to see if I could help - Libby - with her Benjamin Tonks of Auckland family I found these listings - they may help other researchers.
Benjamin Tonks - Mayor of Auckland 1875-1876
NZ Herald 1870:Deaths DIGBY - On Feb 11 at residence of her son-inlaw, Mr B Tonks, Willowbrook, Epsom, Mrs Hester Digby, aged 70 years.Funeral will leave at 5 o'clock this afternoon (Sat) (NZH 12 Feb 1870)
Southern Cross Newspaper Thurs 12 Apr 1860: Benjamin Tonks is listed amongst others - The following persons have proved to the satisfaction of your committee that they eimigrated under the belief that they would obtain land in lieu of passage money: can be seen athttp://nzgenealogy.rootschat.net/southerncross2.htmhttp://nzgenealogy.rootschat.net/southerncross2.htmthe lists of names are those at the bottom of the page. A history of this action can be found at http://homepages.ihug.co.nz/~Sxmitch/Military.htmlhttp://homepages.ihug.co.nz/~Sxmitch/Military.html Listed here is - Benjamin Tonks (by son) deceased No 4 Company, Rifle Volunteers Captain Auckland amount recommended 30 pounds.
Ordinary member of the NZ Institute Philosophical Society 1875: B Tonks (Parnell)
Northcote Rates (1925-26) Shadrock Benj. Tonks - Valley Road Northcote (thinks this is also Shadrack)
Because of his middle name he is probably related down the line?
A son of Benjamin & Louisa Tonks was Benjamin Digby Tonks b. 1856
there is a LDS listing for him as being married on the 26th Jan 1882 in Auckland to Mary Elizabeth Buckland