THAT advert (reportedly the most expensive ever in Britain) uses "Something in the Air" by Thunderclap Newman. I, too, find it quite clever, though BA could've come up with a better slogan than "21st Century Air Travel". You can see the video at http://www.banews.co.uk
Originally, BA used a version of the duet which sounded a lot like Yanni's Aria (HE, too, copied Delibes), and ruined a beautiful operatic piece. Luckily, BA have now come to their senses, and are using the original version in their adverts, or some clever reworkings, i.e. classical guitar, violin...