When people speak of Aer Lingus having a long haul network benefiting from feed from the UK regions at the expense of BA, it's a long haul fleet I can count on two hands.
BA's long haul heavy fleet comes in at around 127. Versus ~ 8 at Aer Lingus. Worth remebering.
IAG want LHR slots for BA/IB/VY, flying low cost economy passengers on ATRs out of BRS to the US is not focus. Any strategic growth is constrained by a lack of capacity at DUB where preclearance at T2 has pain points.