Last year DH and I both got ETAs for travel to the UK. The notice of approval said we do not have to show proof of the ETA for travel to the UK. Since then I've been twice to the UK and DH has been once. No problem, no questions about the ETA.

Last October we flew from Dubrovnik to London and had an overnight layover in London. Once again, no questions. Today we are flying from Malta to London and we will have an overnight layover. When we checked in, they asked for proof of out ETAs. Thank God I was able to search my email and find those, because they really stood their ground.

So regardless of what you've heard, and regardless of your prior experiences, be prepared to prove you have an ETA.

That is bizarre. What airline was that?

I suspect it will happen more often as airlines are worried about passengers being turned away on arrival in the UK meaning the airline has to pay to take them back to where they started.

I hope you enjoyed Malta. my SIL is there now celebrating her birthday. It has become her go to place since my brother died.

https://www.gov.uk/check-eta

I thought the ETA would be connected electronically to your passport. So you show your passport at immigration, or scan it at a machine, and it can see your ETA. Or is it a different scenario you are describing?

The airline can ask for proof at check-in just as they can for the ESTA. As I said they don't want to be lumbered with no admission passengers.

Oh, and it applies to all non UK/Ireland passport holders, not just US citizens

Some routes are higher risk. Flights from Greece,Spain,Italy and I guess Malta to the Uk are likely getting closer looks. All the paperwork.