Cyrano, on Wednesdays the aeroplane could have been sent to Rome, Geneva, Barcelona, and dare I say it, Brussels!
It is not that hard, you know!
Is the EI pilot base in Cork permanent and pensionable (sorry, Jack) or is it a mix with contractors? A teensy part of me is cynical enough to wonder would EI be more content to leave the aeroplane on the ground on a Sunday rather than have to pay the flight crew double pay for working on Sundays but I will admit that is just me being a bit sicko!
As for Frankfurt why would EI try it from Cork if they feel sure the mugs from Cork would take the Midnight Bus etc and I guess it may also be a case where EI are protecting their loads and yield on Cork Heathrow and their feed with BA?