Complex sentence: There had already been a cathedral at Glasgow before Jocelin's episcopate, and the idea that the ecclesiastical establishment before Jocelin was simply a small church with a larger Gaelic or British monastic establishment has been discredited by scholars.
Split into simpler sentences: There had already been a cathedral at Glasgow before Jocelin's episcopate. The idea that the ecclesiastical establishment before Jocelin was simply a small church with a larger Gaelic or British monastic establishment has been discredited by scholars.