they cant, they would have to use a lower denominations, these american projects are on coins that are more like our 20p's which have a high mintage every year, i can't see them doing it on 50p's, looking at the genral minting figures... its usualy around 30-40 million, the olympic stuff is what 82 million? its not possible. i do like the designs on the 2011 issues though, the WWF is 2011 issue in the sets, and is quite a nice design. shame the £5 has prince phillips face on it.. instantly making an ugly coin