ericlday,
Website says £1.50 pos fee per transaction. Now I assume a website still classed as a point of sale? But I also assume Ryanair only debit the card once, so a better deal than using a debit card and paying per person, per sector.
As with most cards, usage in other currencies attracts a 2.5% fee + interbank mark up. Nationwide good for not chargine the handling fee in Euroland & iirc 1% in other countries.