BA and Dublin
BA has not had a mainline presence in Dublin for many years (maybe 10 years) When Aer Lingus was part of the One World alliance, BA had a code share arrangement with it to Heathrow. The final BA link to Dublin was to Gatwick. BA's regional affiliates also gradually withdrew (probably in the face of competition from Ryanair and Aer Lingus when it was going down the low cost route. Similarly British Midland has reduced services to Heathrow to 4 a day from 8 at one time.
It seems that most long haul connection from Dublin is done vai Paris, Amsterdam or Abu Dabi or, westwards, vai and Aer Lingus gateway in the US