Originally Posted by LondonAndy

I have a Tesco credit card, but get more miles using the Paypal card:
https://www.paypal-marketing.co.uk/topupcard/index.htm

It is a pre-paid Visa credit card which you can top-up using your BA Amex card, so you can use it at all the retailers which don't accept Amex.... and you don't get charged a cash advance fee or interest charge.

The only downside that I can see (and I've been using it for 7 months or so) is that you don't get the protection that you would normally get through paying for things with a credit card...