Task: Question Understanding
Input (English): Context : Created by Adrian Hodges and Tim Haines, who previously created the Walking with... documentary series, Primeval follows a team of scientists tasked with investigating the appearance of temporal anomalies across Great Britain through which prehistoric and futuristic creatures enter the present, as well as trying to stop the end of the world. 
Question : The show Primeval originally aired on what network?
Output (English): original network