A mammoth research project is seeking to trace descendants of 250,000 signatories to a pre-famine petition showing their appreciation for an English lord.
The Morpeth Roll was signed by aristocrats, merchants, traders, clergy and ordinary people in 1841, on the departure of George Howard, Lord Morpeth, as chief secretary for Ireland.
Terry Dooley, from the Department of History at NUI Maynooth, said it has the potential to provide a unique insight into Irish life, society and politics in pre-Famine times.
"The Morpeth Roll has significant research potential, whether examined as a pre-Famine census substitute, a genealogy resource, a family heirloom or a politically motivated document," he said.
"Our campaign will unlock the stories of the signatories and what happened to them through, and after, the Famine."
It has been estimated that the life stories of about 90% of the signatories after 1841 is unknown.
The scroll itself is made up of 652 individual sheets of paper glued on to linen to make a 412m long petition - three times the length of Croke Park.
It was rolled on to a mahogany spool and held privately by Lord Morpeth's family in a basement in Castle Howard, Yorkshire, for more than a century.
"The petition was a way of thanking Lord Morpeth," Mr Dooley said. "The Whig party was still popular in Ireland at least up until 1841, and by the time he left there were various associations for reform in Ireland and support for Catholic rights."
Leading names found on the scroll include nationalists Daniel O'Connell, Thomas Davis and Charles Gavan Duffy.