Complex sentence: The years 2010 and 2014 are considered the golden years for sport in the school, having won the Leinster "A" Gaelic Football title against Marist Athlone in Croke Park in 2014 and beforehand in 2010 narrowly losing in the Leinster "A" final.
Split into simpler sentences: The years 2010 and 2014 are considered the golden years for sport in the school. Having won the Leinster "A" Gaelic Football title against Marist Athlone in Croke Park and in 2010 narrowly losing in the Leinster "A" final.