Complex sentence: Laurence Binyon's was son of Frederick Binyon, a Quaker minister, and Mary Dockray whose father, Robert Benson Dockray, was the main engineer of the railroad company of London and Birmingham.
Split into simpler sentences: Laurence Binyon's parents were Frederick Binyon, a Quaker minister, and Mary Dockray. Mary's father, Robert Benson Dockray, was the main engineer of the railroad company of London and Birmingham.