Leprecon is the annual convention of DU Gamers and has probably been running for over 37 years as of 2017. Leprecon was most probably the first gaming convention in Ireland.
The first event was organized by a group led by John Munro. The group mostly consisted of students from UCD and TCD. Gamers were invited to bring their own games for a pre-Internet meet & greet. Organisers made sure to display Napoleonic games, 1/300 micro-armour, SPI games as well as Dungeons & Dragons. The highlight, however, was a competitive D&D game in which several groups of players raced through a D&D maze, complete with sound effects. The event was covered by a Dublin newspaper.
LEPRECON ~1980 Con run in Ireland by Der Garvey and others at Trinity College Dublin. Quite successful by all accounts. May be more to come. - quoted from http://www.badpets.net/Diplomacy/AtoZ/KL.html
Over the years the con has had many different locations and motifs. For many, many years the GMB in the heart of Trinity's campus was home and while the building looked great it was always too small and usually too cold. In latter years, barring one hiccup, the con has taken place in the more spacious and modern Goldsmith Hall, just outside the eastern boundary of Trinity's official campus. This has allowed for a lot more experimentation in the area of special events and it also means that you aren't knocking over wargames every time you turn around.
In 1987 they were on Leprecon VIII. Even then, there was some dispute over whether it had run annually for eight years or if eight events had been run in a shorter period of time. Since 1987, Leprecon has run annually.