They *are* a national ID card, regardless of their availability, having the same status as a national ID card of any other EU country or Switzerland. Any EU country should accept them for travel. If they don't, it's only because they don't know what they are.

http://www.direct.gov.uk/en/Governme...ards/DG_174258

in particular:-

"Using your identity card
By using biometric information (such as a photo) to prove your identity, an ID card makes it harder for people to create false identities.

Your identity card can be used to prove who you are in all kinds of situations, such as:

[...]

when you go abroad - the card can be used just like a passport when you travel within the European Economic Area and Switzerland"

Of course, if today's General Election is won by the Conservative Party, they may be abolished and thus become invalid.

Neil