Complex sentence: Despite the vibrancy of St Peter's Mackonochie was extremely unhappy, he had moved from St Alban's out of a sense of duty and missed his old parish and his self-confidence was waning.
Split into simpler sentences: Despite the vibrancy of St Peter's Mackonochie was extremely unhappy: he had moved from St Alban's out of a sense of duty. He missed his old parish and his self-confidence was waning.