Prince William and Harry are connected to a distant Irish relative on their mother, the late Princess Diana’s, side.

A massive, 170-year-old scroll that was discovered in Dublin provides a definitive link between Prince William, the future King of England, and an Irish relative.

The Independent reported on the scroll, that had been on tour throughout Ireland, and how it connects both Princes William and Harry to a distant Irish relative on their mother, the late Princess Diana’s, side.

The scroll, known now as the Morpeth Roll, was a massively long - nearly three times the length of Croke Park in Dublin - thank you and goodbye note to George Howard, Lord Viscount Morpeth, when he left his post as chief secretary for Ireland in 1841.

In his role, Lord Viscount Morpeth was a popular politician champion for Catholics and their emancipation.

257,000 people signed the scroll upon his departure, coming from all types of backgrounds all around Ireland.

Included in the signatures is one of Henry White of Booterstown, Dublin. Genealogists discovered that in 1919, White’s great-grandson Luke Henry White married Lavinia Spencer.

Lavinia was a sister of Albert Spencer, who would end up being the grandfather of the late Princess Diana, mother of Princes William and Harry of England.

The Irish link to Prince William coincides with that of Duchess of Cambridge Kate Middleton, who also had a distant Irish connection through singer Chris de Burgh - Middleton and de Burgh share common Irish ancestry.

For 170 years, the Morpeth scroll lay in obscurity in the basement archive of Castle Howard in Yorkshire, England until it was loaned to researchers at NUI Maynooth to be conserved and digitized.

The historical document went on a nationwide tour of Ireland where visitors could view it in person, but it can be viewed online through also.

NUI Maynooth Prof Terry Dooley, who worked on the project, said it was believed to be the only such testimonial ever created.

Learn more about the Morpeth scroll here.

* Originally published in 2013.