What is: // the song used in the latest CITROEN C4 advert. // the song used in the Zurich advert // the song used in Greenwing (the main theme song) // the background music used in the Chelsea Flower Show advert (from about 3 weeks-ish ago) // the background music used in the News 24 advert on the BBC // the background music used in the clip of the people doing tai-chi (BBC)