Complex sentence: The film and the dramatics had been largely the responsibility of its producer John Noel, the expedition's photographer but the British mountaineering establishment covered up the reason for the diplomatic rift for over fifty years by pinning the blame on John de Vars Hazard.
Split into simpler sentences: The film and the dramatics had been largely the responsibility of its producer John Noel, the expedition's photographer. The British mountaineering establishment covered up the affair for over fifty years by pinning the blame on John de Vars Hazard.