You appear knowledgable on this .. what happens if the Irish citizen, living in the U.K. goes to France .. does he have to carry an Irish passport to get back in to the U.K.? It's a good idea for all cpts to check passports first
.....National IRELAND (REPUBLIC OF) (IE)
Destination UNITED KINGDOM (GREAT BRITAIN) (GB)
UNITED KINGDOM (GREAT BRITAIN)
Flights from/to United Kingdom to/from Channel Islands,
Ireland (Rep. of) and the Isle of Man are domestic flights.
Therefore, there is no Immigration control.
If arriving from outside the above-mentioned areas:
passport required.
Visa not required.
Non-compliance with entry requirements(incl. forged documents)
will result in fines for carrier of GBP 2,000.- per visitor
and either deportation or indefinite delay for visitor at
point of entry (detention costs at carrier's expense).......
I would say that's a yes!