Complex sentence: He was greatly tempted by the offer, but felt it his duty to remain in England, as the offer came too late for Bennett to make alternative arrangements for some of his pupils, and he refused to let them down.
Split into simpler sentences: He was greatly tempted by the offer, but felt it his duty to remain in England. The offer came too late for Bennett to make alternative arrangements for some of his pupils, and he refused to let them down.