Flight delay claims are still with us despite Brexit. It's the flights that have flown but what might lift your spirits is the prospect of reactivating a refused claim on account of a recent court decision. Have a look at https://www.breakinglaw.co.uk/search/label/flight%20delay%20claims to see how delay claims work and airlines can escape liability for having to pay compensation on the ground that the delay was caused by 'extraordinary circumstances'.
The recent decision comes from the Court of Appeal in a case called Lipton v BA City Flyer Ltd. That involved a flight from Milan to London City. One hour before the flight was due to depart, and before he had come on duty, the captain reported in sick. There was no replacement captain available and so the flight was cancelled. Hence, the delay. The Court of Appeal ruled that this event did NOT amount to an 'extraordinary circumstance' and so the airline had to pay out to the passenger who pressed their claim for compensation.
The decision is likely to put pay to future liability escape for airlines by arguing that the delay was down to staff absence and airlines can be expected to be on even weaker ground where the sickness occurs while the member of staff has already started their shift. All of which means that if you have not already been to court and lost but been turned down by the airline for compensation in a 'staff sickness' situation, have another go at them and mention that Court of Appeal decision. And don't mention me!