Simplify the following text for a Grade 6 native English-speaking person.
Original: It was originally broadcast on 1 January 2007 . Since the series was commissioned before the script for the episode was written , it is not a pilot , but a holiday special , and serves the introductory functions of a pilot .
Simplified: It was broadcast on 1st January 2007 and although it is written as a pilot episode , it is not .