Magic stamps

icHuddersfield - SECRECY surrounds the Magic Circle like ... well, a circle.: "The centenary of the Circle was brought to national attention back in March with the production of a special set of 'magical' interactive stamps. The First Class stamp used a technique never before seen on a UK stamp - rubbed with a coin it revealed either heads or tails. Two other stamps perform their own magic and 'change' when heat from the hand is applied, and the final two are optical illusions."

Wonder what happens when you lick the back!