Don’t know reason for cancellation sorry but had an MCO-LGW cancelled myself a few weeks back, we were put on later flight but met someone at the airport who managed to convince BA to switch his family to TPA-LGW given the circumstances, just wanted to add for awareness in case of any use, I guess any FL-LON pair could be requested. Also MCO lounge was rammed so we ate at the beach house restaurant and put in a claim, BA paid without fuss, however YMMV.

Hope they get home safe!