Complex sentence: He attended primary school at Loreto and then St Kieran's College, where a rebellious streak combined with an after-school occupation of promoting concerts of 19060s pop acts like Thin Lizzy, Them, and Granny's Intentions caused some friction with the clergy.
Split into simpler sentences: He attended primary school at Loreto and then St Kieran's College. Here Leahy combined a rebellious streak with an after-school occupation of promoting concerts of 1960s pop acts like Thin Lizzy, Them, and Granny's Intentions caused some friction with the clergy.