The problem I guess is that a lot of FRs do three or even four trips per day, therefore delays mount storing even more problems later on. It’s notable most of the first wave departed eventually and cancellations sat in the second/third wave. Probably crew hours also have an impact. Their size also means they’re disproportionately impacted. Also a fair few of their flights head north and east which is where further trouble was in store. Southbound were less affected.
Its fair to say they weren’t alone with problems, the earlier Jet2 departures had delays between one and five hours, Thomas Cook almost three hours, TUI 90 mins, Eurowings two hours.
What doesn’t help but makes a nice story for papers is people insisting on queueing to re-book. They would be far better off doing it themselves on their phones, heading home or heading somewhere else.