Published Monday, 28 April 2014
Declan Donnelly is best known as one half of presenting duo Ant & Dec. (© Getty)
Donnelly's family moved from Derry to England in the 1960s, but the newly released records trace his family back 180 years to his great-great-grandfather James Donnelly.
Irish family histories are notoriously difficult to trace because of the destruction of the Public Record Office in Dublin during the Irish Civil War on 30 June 1922.
Two huge explosions sparked a fire that ripped through the Four Courts, destroying millions of records and hundreds of years of Irish history.
Researchers examined census returns for Derry in 1831 and identified James Donnelly as the head of household 49 in the townland of Stramore in the parish of Ballynascreen.
Records show he was living in a parish in the county with three women, most likely his relatives, and the religion of all four was recorded as Catholic.
It was also recorded that in 1839 James Donnelly married one of his neighbours, Ellen Hagan, and the ancestry continues in the parish until Dec's mother Annie Henry married his father Alphonsus Donnelly in 1960.
There was no record of the professions of anyone in the homes or information on those who might have died or emigrated in the previous 10 years, as happened in 1841 and 1851.
Brian Donovan, from findmypast.com, said the 1831 census could yield treasures for the Donnelly family tree and hundreds of others.
"We would need to know these people are in the locality before we try and go looking for them, and we knew about Dec so we went looking for his past and this is what we discovered," he said.
"The key thing is that this is one of the most unique insights into pre-famine Ireland - a world that was changed fundamentally."
© UTV News