Nokia Music for Windows Phone - Why was £1 / 1 GBP charged to my credit card when I added it as a new payment card in Nokia MixRadio?

Every time a new card is stored, Nokia process a low value (1GBP) authorization to verify that  the card details are correct. However, it is just an authorization and not an actual charge. In some cases, this activity may appear on your bill or statement but you are never actually charged the money.