John McMahon’s biography on the Players page here mentions his long association with the Leinster leagues: in the Armstrong Cup with Kevin Barry from 1956-76, and in the Heidenfeld Trophy with Lucan from 2005 onwards.
Here is one of his Heidenfeld games, which John sent some time ago, from a Dundalk Drogheda – Lucan match, featuring a fine win and a picturesque finish.
28. ?
White now erred with 28. Re3? (after 28. f3, Black stands much better but White can resist), and after 28… Nf5 Black was already winning.
The continuation 29. Re2? allowed a king hunt and mate in five, via 29… Nh4+ 30. Kh3 Qf3+ 31. Ng3 Qg2+ 32. Kxh4 Qxh2+ 33. Kg4 Rf4 mate.
[Click to replay the full game.]
[Update, January 26, 2023: Mark Gonnelly, via email, pointed out that there was no Dundalk team in the Leinster leagues at this time, and that instead this was a Drogheda – Lucan match; many thanks.]