Tong visited Sir John at home in 1530, and wrote down what he was told on blank sheets. The manuscript used for the book was a copy, but it was an early copy, with no indication of being doctored at all, though copyists can never be relied on for exact spelling. There's another copy, but they weren't compared. However, this is one of the most reliable of all the published Visitation books.
Harleian #4 (Vis Notts) contains a number of known major errors. The manuscript it's based on was a workbook compiled by Richard Mundy, an arms painter who lived about 1630. Mundy was a friend of the heralds and could get access to their Visitation records. But he didn't copy them verbatim. His style was to combine them, and make additions of his own, sometimes whole extra pedigrees from dubious sources. In this case, he converted the 1569 pedigrees from written-out format to chart format, and then joined on the 1614 charts. But the record for 1614 had already been doctored at the College.
It's unlikely there was a Dunham pedigree in the 1569 record, as the last of the line was dead by then. There was one in the 1614 record, because it's also in another copy, made by other arms painters. But it's obviously an insertion, so we don't know where it came from. Especially we don't know why Sansford was changed to Stanford. The double-f means nothing because there's "Godffrey" Foljambe in the same chart.
Harleian #16 (Vis Yorks) is from a heralds' workbook. It was started by Flower, who copied out previous Visitations and added his own. Then it passed through various hands and a lot of additions were made. Many charts were extended and many extra pedigrees were added. Some of the added material is guesswork and some is blatantly fake.
All the same, it would have been an interesting book if edited properly. But Norcliffe took away a lot of the value by rearranging the pedigrees alphabetically and not noting the different hands. So we're left with important early information all mixed up with total junk, and we have to try to figure out which is which. In general it's iffy to rely on anything in this book that you can't find in a better source.
The compiler of the Dunham chart was aware of a line from Sir Edmund Sandford back to Edward I (so he thought. It's not right, but the heralds were all at sea with ancient aristocracy. The editor's correction isn't right either). So identifying Robert Dunham's wife as Sir Edmund's daughter looks a bit "convenient".
There's another Dunham chart in the manuscript that passes for Glover's Visitation of 1584-5, but it's copied straight from Tong and not extended at all. However, it does say "..... dau. of ..... Stafford, of co. Derby", so Isaac can't be blamed entirely for bringing Staffords into it.
