For those people who don't drive or don't want to take their passport with them just to pop down the shops it seems there is (what claims to be) an official ID, but looking at the website... it seems like one hell of a lot of faffing about and little there convinces me it's even genuine... For all I know it's an elaborate scam. Even if it is genuine I really wouldn't feel comfortable sending the amount of information they require along with my credit/debit card number for some Muppet to leave on the bus along with the private details of 450,000 other people.
Of course the under age wine connoisseur has no problem obtaining a fake ID which looks better than some of the official ID cards around. There are dozens of sites just like this one offering "novelty" driving licences and such like. Very handy if you're 15 and fancy driving your mates down to the Dordogne on a tour of vineyards.
I do find myself wondering if you order one of the "fake" Proof of Age cards (driving licences are another matter) and all the info contained on the card is genuine... Is it really a fake one?
The fake ones are cheaper and there's no faffing around finding an eligible verifier to sign your photographs, photocopying your birth certificate, passport, driving licence, medical card etc... and no need to send credit card details, because they take postal orders.
So if challenged for ID you offer one of these "fake" IDs or one you've designed yourself and printed out on your inkjet and laminated and it contains all genuine information I can't see any problem. Of course the retailer isn't under any obligation to serve you even if you have the "real" citizen card.
If I have time later I'll tell a little story that involves ID cards, it's about two train journeys I made a few years ago. If I don't have time to write it here, buy me a drink next time you see me at a pub or club and I'll tell you the whole story. But that may depend on you having some ID on you to buy me a pint.