The programme began in World War II with the idea that playing non-stop popular/light music at an even tempo would help factory workers become more productive.
[1] From October 1940 a theme tune, Calling All Workers by Eric Coates, was adopted to begin and end each episode, arranged by the performers of the day.
Many combinations made hundreds of appearances, notably Pasquale Troise and his Banjoliers, George Scott-Wood and His Music, Cecil Norman and the Rhythm Players, Bernard Monshin and his Rio Tango Band, Anton and his Orchestra, Bill Savill and his Orchestra and Jack White and his Band.
Although the programme became very popular with domestic audiences and later with motorists, it was aimed first and foremost at the factories, and strict rules were applied: predominantly familiar pieces, nothing lethargic, consistent volume, avoidance of overloud drumming (which could sound like gunfire), and generally cheerful programmes to which workers could whistle or sing.
The song "Deep in the Heart of Texas" was banned from the show, because of the potential danger of production line workers taking their hands away from their work or banging their spanners on the machinery to perform the four hand-claps in the chorus.