Link gives more info, small extraction -
"Generous designers at George were also offering a free pair to anyone called Sienna. All customers have to do is to bring in their birth certificate to their nearest George store and collect a pair gratis."
I was wondering if "George Store" meant a special George clothing only store but if you use the search tool on http://www.george.com/stores/
their definition of a "George Store" appears to be any ASDA store that sells George clothing.