Not sure how to phrase this without sounding snarky, and I really don’t mean to be

The have registration plates

They have registration stickers

Both of these come from the DLT I think

If you see someone without a registration plate it hasn’t been registered or they’ve fallen off. If you see someone without a current sticker it hasn’t been renewed

Some European countries don’t have the stickers anymore - but registration needs renewing nonetheless

@NaLaa ****

it depends on the country, but isn't law in many places. I know dual UK/Oz citizens who go to Oz on their UK passports - the advice is to travel on an Oz one, but it is only advice. Similarly, others routinely travel back and forth between the UK and Sweden on the "wrong" passport without issue (although Brexit may make that more awkward). If you are a citizen, passport or not, once you get to the border, it would generally be illegal to turn you away. You might be held up for a while while they verify your citizenship, but I've never heard of it happening #notlegaladvice

This happened to my girlfriend with another airline, Norwegian Airways I think. When I contacted them, they basically said I shouldn't have bothered even calling them, as long as the name is correct who cares. I guess, when you think about it, most passports and IDs don't even include the prefix at all