Its ounds to me an awful lot like the Montgolfier Brothers.
First album - "Seventeen Stars" is simply beautiful; second album "The World is Flat" almost as good.
My suspicion is that itis indeed them who have done a commisioned piece for the ad agency. I have emailed the band but no reply yet. If you want music like this though - go an buy "Seventeen Stars"!
D.
Sorry folks - it isn't the Montgolfier's (Email from Mark Tranmer of the band) - its a hell of a track though.
Still, The Montgolfier Brothers stuff is excellent - give it a listen anyway!