The seventies were a Golden Age for cerebral documentaries with such outstanding examples as The Ascent of Man, Cosmos and Life on Earth. Such shows were content driven, relying heavily upon the quality of the script along with the charisma and gravitas of the presenter. Jacob Bronowski, Carl Sagan and David Attenborough were exemplars of this. Jeremy Isaac’s The World at War is another archetype of quality documentary film making from this decade.