Performer Paul McDermott and former foreign affairs minister Alexander Downer have made a "gentlemen's pact" to end a dispute between their ancestors that dates back more than 150 years.
Mr Downer recently attended one of McDermott's shows during the Adelaide Fringe festival, which included a story about the connection between the pair.
The show was on at the Queen's Theatre, which was built in 1840 and is mainland Australia's oldest remaining theatre.
It was used as a court between 1843 and 1850, and during that time McDermott's great-great-great-grandfather Michael McDermott appeared charged with drunkenness and threatening to kill his wife, Mary McDermott.
Later, in 1868, Michael and Mary McDermott's son, Patrick - Paul McDermott's great-great-grandfather - appeared before Insolvency Commissioner Henry Downer.
The case for the creditors was brought by Henry Downer's brother - and Alexander Downer's grandfather - Sir John Downer.
Sir John later became the premier of South Australia and a senator in the first Australian Parliament, while Patrick McDermott declared himself bankrupt and spent time in jail.
McDermott found out about the connection during his 2014 appearance on the SBS show Who Do You Think You Are?
'Justice' for McDermott's ancestor
McDermott had been telling the story for several shows before the former Liberal opposition leader turned up to one of his recent performances.
The comedian pointed out that Mr Downer was in the audience after recounting the tale.
The audience "howled at the unfairness", McDermott said, but Mr Downer "took it very well".
"It could have gone either way," McDermott told ABC Radio Adelaide's Ali Clarke this morning.
"This felt like justice for the poor Irish scallywag.
"It felt like the end of a circle. This felt like something historic and wondrous coming to an end."
The pair caught up after the show.
"Basically, we made a gentlemen's pact that the past had been dealt with on that particular night and peace and harmony reigned between the two families - but who knows what will set us off again?" McDermott joked.
Coincidence that Downer attended
Mr Downer said it was a coincidence that he was at the show.
He had not heard about his grandfather's case or that McDermott would mention it during the show.
"It was fun - an amazing story," Mr Downer said.
"I had a chat with him later."
He pointed out that it was not much of a dispute, since Sir John was a barrister who represented many clients, all of whom deserved legal representation.
McDermott is now playing a second show for the Adelaide Fringe, called Paul McDermott PLUS ONE, with Glenn Moorhouse at the Rhino Room.
It has three more shows before closing on Saturday.