Hi everyone, thanks for replying.
I was given the chart by my mother, who is now very elderly. She does not know where it came from. My immediate family left NZ for Australia(where I live) in the 1960's and I have never had much contact with my NZ relatives. Few are left. So very sadly I am not in contact with anyone - and have no idea where the chart originated - hence my inquiry online.
One of the trees on Ancestry is mine, and I have been in contact with other researchers, but found no-one who (a) has another copy of the chart or even knows about it or (b) can tell me anything more about John White and Mary Nellen from family knowledge or previous research.
I agree with you about the printouts and certificates: interestingly I did not send for these but was given them by a White family member I contacted who could tell me nothing about where they originated, did not have a copy of the chart, and added that they had come to a dead end in finding more about John and Mary. Now, looking at them more closely, I can see that whoever obtained them did so in 1993, possibly at the time all of that huge amount of research was being done which resulted in the chart. Or the date could be a coincidence too! I will eventually send for the originals.
I do have a copy of the original marriage certificate, and their ages are for John White - 'full' and Mary Nellen '-'. So I obtained their Intention to Marry and found there that John claims he is 23, and Mary that she is 18, and it is stated also that there was 'no person to give consent' in her case. I have contacted members of the NZGS and there are a couple who have these names as research interests, but after exploring a few leads, I found no connections at this stage.
Using the information on the death certificates - information often given by family members - I find that Mary was believed to have been in NZ for 54 years, which would make a time of arrival for her as 1863. She was listed as being 74, which puts a possible date of birth as 1843. However in 1865 when she married, she said she was 18 which indicates a birth for her in about 1847. I feel more inclined to go with her claim that she was 18, and that she was a possible new arrival to NZ. I have not been able to find her on a passenger list from Ireland to NZ so far.
John's death certificate says he was in NZ for 52 years, making a time of arrival as possibly 1864. This does tie in with information from a newspaper article I found saying that he had arrived in NZ from Australia about that time. His age in 1916 is given as 82, giving him a birth year of 1834 - but his own information is that he was 23 in 1865, making a birth date about 1842. Mary is listed as 78 years old at the time of his death (she was about 69/70)...... ah, families.....
So my line of inquiry now is trying to find a ship that John may have come to NZ on, from Australia. There are a few possibilities (none with ages that match!), so I need to look at the films of the records that exist. I have also tried to find Mary on a passenger list from Australia, but no luck there. This does not mean she didn't arrive from Australia..... not everyone was listed, records are not necessarily complete for shipping. Her name, too, with the variable spellings, does not make for easy searching....
John and Mary are my hardest relatives to research yet, but I live in hope. Cheers!