Originally Posted by
corporate-wage-slave
Yes, not least because the flight number will change, so it would be difficult to argue the flight has not been cancelled. There is some jurisprudence on this too, and basically not in the airlines' favour.
The journey starts in Dublin and if all on one ticket it’s highly likely that a DUB-LHR-MCO reroute would be as quick, if not a quicker transfer than via LGW. If the OP were rerouted on BA metal all the way (I assume LGW-DUB is an EI service) Via T5 the MCT would be a lot less and given the frequency might be a better journey overall.