Complex sentence: Lethbridge became increasingly disenfranchised with the academic and professional archaeological community over the widespread rejection of his "Gogmagog" discovery, believing that an attitude of what he called "trade unionism" had caused most archaeologists to reject independent thought.
Split into simpler sentences: Lethbridge became increasingly disenfranchised with the academic and professional archaeological community over at the widespread rejection of his "Gogmagog" discovery. He believed that an attitude of "trade unionism" had caused most archaeologists to reject independent thought.