Did you know that if your flight is delayed for reasons other than those outside the airline's control, such as a volcanic ash cloud or bad weather which stops all flying, you are entitled to compensation? For a short delay, this may be only a voucher for refreshment but for a delay of more than 3 hours on a flight shorter than 900 miles you would be entitled to 250 Euros per passenger.
Sometimes carriers deliberately overbook flights and then bump some onto a later flight.
Details are given on the website of the Civil Aviation Authority. The CAA also has a team who assist passengers who have a claim against an airline. Typically airlines will ignore a claim until it becomes clear that it isn't going be frogotten so it pays to persist. You will need proof that the flight was booked and paid for and that the passengers checked in on time. So keep print-outs, boarding pass stubs etc.
These arrangements apply to flights within, into and out of the EU with airlines pricipally based in the EU and apply to discount and "no-frills" airlines.
It's best if everything goes smoothly in the first place but £220 each sugars the pill.