Light music was often played at seaside resorts. It often consisted of arrangements for orchestra of popular songs. It was music that was supposed to be popular, music that a wide audience would be able to enjoy.
In the 1930s, when the BBC started broadcasting music on the radio (which they then called "wireless"), light music became very popular. In 1945 the BBC Light Programme was started. One very popular programme was called Friday Night is Music Night, with music played by the BBC Concert Orchestra. and Music While You Work was also a very popular programme.
Eric Coates is a good example of a composer of Light Music. His piece "By the Sleepy Lagoon" became the signature tune of a radio programme called Desert Island Discs. Arthur Wood's "Barwick Green" became the theme of The Archers.
Light Music is similar to what is called Salon Music (German: Salonmusik) in Europe.