I agree. I tried to push her to stand her ground, but she got a little scared by the intimidation of the gate agent who said she would not be flying without providing alternative ID. The agent said this was standard for all Italian passport holders. I told the gate agent that such a policy is discriminatory against the nationals of another EU member state and not legal. She checked with the other gate agent (who appeared to be her senior or supervisor) and the other agent confirmed that she must verify an alternative ID.

Once we were onboard, there was another passenger who was similarly hassled for alternative ID by yet a third gate agent who entered the aircraft once boarding was complete. I didn't catch that passengers nationality.

I am inclined to report this to the EU's SOLVIT, and file an official complaint with Norwegian and the European Commission. I'm wondering if this is a UK policy that's being communicated to the airlines (I have noted other harassment at the UK border of Italian citizens, and especially ID card holders) or if it's a few gate-agents who have been misinformed of some policy.