Ireland has been a tricky nut for BA to crack since the end of the Aer Lingus / BA duopoly in the early 90s. BA *inherited* a return to Ireland when the independent CityFlyer Express became a BA franchise holder. This route was maintained by BA mainline at LGW on the small B737-500, however when that aircraft was retired and "partner" Aer Lingus returned to LGW-DUB again (for the nth time), BA was happy to drop Dublin as the B737-400 was too big and any feed was maintained by EI.

They then had a half hearted crack at it again from LCY on a leased 146 from Flightline but again it was not to be.

This is slightly different, as it's BA operating a mainline BA aircraft and feeding LHR long haul from a major European capital. I think the key difference this time, is their heart is in it. With the CEO of IAG being himself, I could not possibly begin to speculate to even wonder why what may have changed.....