For anyone looking for a commission-free credit card to use abroad, I just noticed that you can get £15.60 cashback when you apply for the Post Office card through www.quidco.com. If you don't already have a Quidco account you will lose £5 of this as annual fee, leaving £10.60 for you.

There are also doing 0% interest on all purchases for the first 3 months. The card is issued by Bank of Ireland so unlikely to conflict with any existing loyalty-based card you have (ie its not MBNA!).