In 1986 it was decided to make the Irish championship a 10-player invitational all-play-all. There was also a separate qualifying tournament that decided at least some of the places (one?). In the last round Colm Daly (White) and Jonathan O’Connor met, with Jonathan on 4½/5; I’m not sure what Colm’s score was.
It was an odd game. Jonathan gave away an exchange for no particular reason (19 … Qf6?) and was dead lost. In the diagrammed position, White, to move, can finish off nicely via 56. Nxf6! Bxf6 57. h5, e.g., 57. … Be7 58. hxg6 (and if 58. … Nh6, 59. Qxf7+! is quickest). Instead Colm blundered with 56. h5?, and after 56. … Ng5 57. h6+ Kh8 compounded the error with 58. Qg3? Nxe6, losing. Instead 58. Bxg8! would have kept him in the game, e.g., 58. … Nxf3+ 59. Rxf3, when 59. … Kxg8 60. Nxf6+ is about equal. Thus it was that Jonathan qualified for the 1986 championship proper.
(The source is a collection of almost four hundred of Jonathan’s games from 1978 to 1996 that he gave me some considerable time ago, for which many thanks.)