‘Rock Around the Clock’ at 70. It played on national TV from Connecticut.

‘Rock Around the Clock’ at 70. It played on national TV from Connecticut.

It was 70 years ago this month that Sgt. Pepper’s predecessor really taught the band to play. That was when “(We’re Gonna) Rock Around the Clock” by Bill Haley and His Comets became the No. 1 song on the newly published Billboard pop chart. Seven decades later, the song is recognized as the spark for the explosion in pop music that followed. The story of how a song that started as a neglected “B” side of a 45- rpm single became one of the all-ti…