Originally Posted by
NickB
Under EU rules, documents such as passports and ID cards only have evidentiary value. They are not a condition of access to the country. If an individual is in a position to establish that he is an EU national by any other means, then entry to another EU Member State cannot be refused. There is a case decided by the CJEU a long time ago (Giagounidis is the name of the case) regarding a Greek national with a Greek identity card which, at the time at any rate, was only valid within Greece and did not allow the holder to travel. The Court found that Germany could not deny entry and residence on its territory with someone in possession of such a document, since it established that the individual was a Greek national and therefore an EU citizen entitled to free movement.
I would have thought that the same would be true of an expired ID card, as long as we are not talking of an ID card that expired eons ago. If so and if the OP was refused access to the plane with such a document, it seems to me that this would be: (1) either because BA consulted UK immigration and UK immigration said no, in which case UK immigration are prima facie in breach of EU law or (2) BA did not contact UK immigration or contacted them and refused entry despite UK immigration saying yes, in which case BA would seem prima facie to be in breach of its CoC as the OP had sufficient documentation to enable him to travel.
I think you're getting a bit confused. The OPs ID card was expired. Therefore BAs condition of carriage is that a valid travel document is required. If there isn't one then they are fully entitled to refuse travel.
UK immigration's advice would be to refuse travel and advise the person to obtain an emergency travel document. Note, they are not denying entry as it hasn't got that far. They can hardly be expected to grant entry remotely and therefore advise BA to let the person travel, except in very very exceptional circumstances. Once they've established his EU identity then he will be allowed entry.
He needs an emergency travel document.