Complex sentence: Penelope Betjeman-wife of the poet laureate John Betjeman-showed him the border country of Wales, and thereby helped to contribute to the gestation of the book that would become "On the Black Hill".
Split into simpler sentences: Penelope Betjeman-wife of the poet laureate John Betjeman-showed him the border country of Wales. She helped contribute to the gestation of the book that would become "On the Black Hill".