From the Dawn of Man to the Dark Ages - This part was recorded and completed, but not originally used. Instead, bits of this episode and the next one were combined into a new episode so that the series originally aired as a six parter.
From the Age of Kings to the Normal Conquest - This part was recorded and completed, but not originally used. Instead, bits of this episode and the previous combined into a new one so that the series originally aired as a six parter.