When did Popular Music become popular?

There were folk songs that people knew that were passed down from generation to generation, and there were the Music hall songs from the Nineteenth Century known and sung in urban and industrial communities up and down the country. But popular music, that which cuts across geography and class and even age, seems to have come with the advent of the radio and the record player.

Donovan was played on the radio. I have never bought a Donovan record, never been at a Donovan …