"Of course," we announced airily, "it is my sept, the Miltown Malbay O'Briens who are the direct descendants of Brian Boru." The 200 or so Tipperary O'Briens crammed into the tiny pub in the Glen of Aherlow went quiet.
But in the interests of historical accuracy it was important to share with these "Tipperary O'Briens" the knowledge that the last great High King of Ireland, Brian Boru, was a direct antecedent of mine.
There are many supports for the theory that Brian Boru was indeed my direct ancestor. First, my father once told me so. Second, Brian was slain in his tent while praying at the Battle of Clontarf. My father's father lived in Sutton which, as every student of geography knows, is up the road from Clontarf.
As most students of history will know, there are also "estate O'Briens", those who lived as tenants and assumed the name of their landlord. In retrospect, it probably wasn't such a good idea to explain this to the Aherlow O'Briens in the early hours of a Sunday morning in the local pub.
Mr John O'Brien, organiser of the gathering which continues until next weekend, claims the Aherlow O'Briens have been in the Glen of Aherlow for a millennium. Or since about the time that Brian Boru was slain. Against that level of local knowledge, a reporter fleeing for his life in the dark would have little chance.
But there was no need to worry for this is the stuff of clan gatherings, a business of claim and counter-claim all backed up by an exchange of family folklore and carried out in a holiday atmosphere much to the delight of tour operators.
"Actually, this weekend is not really a clan gathering as such" said Mr O'Brien. "We are all the one family who are descendants of Patrick and Briget O'Brien who were married in 1893 and who lived in the Glen of Aherlow."
"But there is a full O'Brien clan gathering being planned by Lord Inchiquin for next year," interjected Mr John Bradshaw, a board member of Clans of Ireland and driving force of the Tipperary Clans office in Tipperary town. "That'll be a grand affair with people staying at Dromoland Castle and O'Briens coming from all over the world." Dromoland is the ancestral seat of the O'Briens and home to the earls of Thomond, the lords Inchiquin. It is now a luxury hotel.
"There is some mystery about the number of children Foxey Pad, as he was known, had", said John O'Brien, returning to the immediate matter of his family. "Sixteen survived to adulthood, three died young and there is a suggestion of three stillbirths." The reason there is only a "suggestion" of three stillbirths is that the Roman Catholic church did not baptise stillbirths, so they did not appear on parish records. The Aherlow O'Briens are well represented in the parish records, stretching back to before Catholic emancipation to the mid-1700s, when the religion was not allowed to practise its rituals in public, much less keep records.
Foxey Pad's children went to the United States and to Coventry in England. Before they emigrated, his daughters apparently went to work for a vet to earn the money to emigrate. The vet then sent them to his son, who was a doctor in Coventry. Because he was Irish, he could be trusted to look after them and ensure they remained in the faith.
This week their children and grandchildren have returned to the small homestead which is still occupied by a branch of the family. During the week one cousin, Father Joe O'Brien, will say Mass in the yard. A video of the proceedings will be made by another cousin. On Sunday night, even the band members were 'Briens.
Also in the small local pub on Saturday night was Mr Barry O'Brien, originally from Coventry but now working in Silicon Valley in the United States as a correspondent of the Sunday Times. Also from the United States was Breda Sampson, nee O'Brien from California, her sister Hannah Galvin from Aherlow and Morgan O'Brien, a publican from London. The Bradshaw family from Dublin - part of the family of the golfer Harry Bradshaw - were there, as were Brigid McGeechan and her family from Glasgow.
Foxey and Brigid now have more than 300 descendants worldwide, according to John O'Brien. The gathering took two years to organise involving much contact between John and his cousin Hannah in the Glen.
"It was well worth while though," he adds. "After all, it is a historical fact that the Aherlow O'Briens are the direct descendants of Brian Boru."