Complex sentence: Stafford was the illegitimate son of a Wiltshire squire, and required papal permission before he became the rector of Farmborough, vicar of Bathampton and prebendry of Wells.
Split into simpler sentences: Stafford was the illegitimate son of a Wiltshire squire, which meant that he had to get the Pope's permission to become a clergyman. Then becoming the rector of Farmborough, vicar of Bathampton and prebendry of Wells.