Aer Lingus upgrades at check in

An upgrade at the airport is unlikely. However, on online checkin sometimes you can change your seat and pay extra. Recently. I was able to upgrade for €250 on the outbound leg, as people were less concerned with the day flight, but there was zero chance on the way back for any 3 digit sum. August is not a good time.

That might have worked 20 years ago - no chance now.

I've seen a few people offered complimentary upgrades. On my way over last year, the girl behind the desk was ripping up boarding cards for a couple who refused a complimentary upgrade. On my way home (same trip - in April) 3 people were upgraded. Only know this as the person in the seat in front of me was 1 of those people and she was absolutely delighted!!

So I'd say there is a chance.

Not really comparing like with like - different airlines, different geographical locations, different operating procedures.

It also depends on the aircraft being used - which can be changed at the last minute