Some Irish users’ cards appear to be UK registered so sterling is the default currency, others Euro. My card is US registered and in Euro, go figure. When you are paying with a sterling card at a Euro merchant with Direct Currency Conversion on their terminal the merchant can process the transaction in sterling at a terrible rate for you. Merchants get commission on DCC transactions. Contactless transactions are always processed at the local currency. At least you were given the option of paying in Sterling, often the merchant will just process it at the DCC rate and rip you off.