whiskygalore did lots of work to find out more: Having trawled through various press releases on the net, the script in 3 of the 4 adverts is based on parables ( Aesop's Fables-type stories). The 3rd advert [rain, cenotaur (sic)] features Shakespeare dialogue. The link posted below contains a telephone number for Barclays Press Officer, for anyone wishing to take this further & also the name of the ad agency responsible for the campaign.
http://www.pressi.com/int/release/47917.html