Thanks to all for useful advice.

Hope it doesn't all go pear shaped after the next elections the day after I arrive!! think I'll be carrying cash

It's worth bearing in mind that, under current circumstances, cash will be most useful in most circumstances in Greece. While one car hire company insists on cards then there will be plenty of other businesses who will insist on cash.

Generally a prepayment card would not be accepted as it is a form of withdrawing from a cash account and it is not a credit card. Some prepay cards issued in the UK are not recognised abroad. A normal full credit card is required for car hire as it acts as a form of identification and confirmation of name and address if the rental or hire office access the account details through their Visa or MasterCard links, and only a credit card account and authorising service can hold the collision damage excess fees often seen as amounts like £250 or £600 and not charge them to the account at the time of hire, but may become charged to the account in the event of a collision incident during the hire period

Maybe yes, maybe no. The company probably wants a card that they can charge for the cost of any accidents as well as the hire charge. Do you trust the hire-car company? Are you willing to dispute any false charges?

I am thinking of hiring a car in Greece, the companies requires a credit card in the name of the driver, would a prepaid card be accepted?