Complex sentence: He joined the show again on 9 October 2013 for the 4,000th link which was "Dear Prudence" by the Beatles, the date coincidentally being John Lennon's birthday.
Split into simpler sentences: He joined the show again on 9 October 2013 for the 4,000th link which was "Dear Prudence" by the Beatles. The date coincidentally being John Lennon's birthday.