In most UK airports it is possible to pay in Euro as well as Pounds. However even credit card users are now given the option to pay in Euro. This seems a bit strange but it may suit some customers to have the transaction posted in Euro rather than a foreign currency. In addition it saves them any extra or hidden charges that their credit card company may include. Whether or not this option represents good value depends on the extent to which your credit card company screws you and the Euro price offered. Anyway Stansted Airport screws you more on the rate than Visa does. So now you know. Ryanair, incidently, always charges you at your home rate even if the ticket is priced in Pounds. At the exchange is at a rate that Ryanair deems appropriate.