Originally Posted by
PGberkshire
Regardless of the CTA, Ireland systematically checks passports/IDs of arriving travellers from the UK.
If arriving at terminal 1, it will be necessary to re-clear security. If arriving at terminal 2, it will not – and there's also dedicated passport checkpoints. So if one is worried about security delays, booking your first LON-DUB on EI is an option to consider.