In third place was the Live Aid concert broadcast in 1985. Number four was the 1938 U.S. broadcast of Orson Welles rendition of "War of the Worlds" by H. G. Wells.
Number five was live coverage of the 1989 Hillsborough Disaster on BBC radio. The rest of the Top 10 include a prank call from Russell Brand and Jonathan Ross, a 1939 speech by King George VI, a deejay who refused to play a song because he considered it obscene, and two moments by BBC radio presenter Chris Moyles including a rant about his pay.
You can read more about each incident at dailymail.co.uk.