Aer Lingus has a lower cost base than BA and if tickets also sold on BA website could prove fruitful.
An interesting idea. If EI can move an A319/A320/A321 from 'A' to 'B' at a lower total cost than BA, is it possible that we could then see IAG shaping their operations so that BA & IB move away from domestic & European routes to focus on long haul from their respective hubs with EI & VY (along with their respective sub operations and those of BA & IB) acting as the feeders into them?
JAS