Happened to me a few times, Brittania 767 went u/s on the way back from Tenerife - GLA, had to land at Gatwick. Brittania brought another 767 in from their base. Only issue was it was a shorter aircraft.... fortunately, some had decided to get hire cars/train home (The flight was already 14 hours delayed by this point)
Loganair EDI-Orkney cancelled as inbound aircraft fog bound at orkney - offered overnight stay (I went home) and flight put on early next AM. I seem to recall they put an extra flight on.
After snowmageddon in March, EZY put an extra Bristol to Edinburgh flight on too.