Originally Posted by FlightDetective

Aer Lingus are quite rigorous about enforcing it.

If you have a Saver fare and did not purchase cabin bag to bring into the cabin, you will have to check it in. Otherwise they will charge you the hold baggage fee if you try to bring it through the gate and it'll be gate checked.

If you purchased to have your bag in the cabin / have the cabin bag allowed in the cabin per your ticket, you cannot then elect to check it in as hold baggage, if you don't have hold baggage included/have paid for a hold bag.

A lot of people think that if they have the cabin bag permitted into the cabin, that they then have the option to bring it in the cabin or check it. They are wrong. Whatever product you have - either bringing it in the cabin or checking the cabin bag into the hold - is exactly what has to happen with the bag. No variation from that at all.