John Joseph McMahon died in 1981, having been born on 29 September, 1907. He passed away in Killybrackey, which is a small town heavily associated with the McMahon family of Ulster.

Killybrackey is located in the “barony” of Dungannon – a barony being a subdivision of a county in Northern Ireland. The gaelic spelling of Killybrackey is Coill a Brocaigh.