Originally Posted by Mr A Tis
The aircraft used was operating a "W" pattern from Cork. Passengers were told it would operate 2 hours late, when in fact the aircraft was still parked at Cork yet to reach Nantes then Manchester.

Should the passengers have been told what was going on? Yes, absolutely - I agree with your wagging finger. As noted above, no excuse for keeping pax in the dark. As they say, though, "never ascribe to malice that which is adequately explained by incompetence."
Should the airline have subbed in another aircraft? Not sure that would have been the right decision. I think if it had been my call I'd have operated 5 hours late but tried to ensure that the pax were given a choice of waiting for the delayed flight (with correct information) or getting a refund. (Disclaimer: I'm not familiar with what EU delayed-boarding compensation would prescribe in this case, if anything.)