327 shows reason for delay as ‘late arriving aircraft’. Can they still claim extraordinary circumstances or does that only apply to the original flight, in which case EU261 compensation would apply to this one in addition to Duty of Care? I remember a debate on FT after the December LHR debacle but not sure if there was a definitive conclusion reached through a court or through arbitration.

The return leg of a flight that got disrupted outbound counts as ‘extraordinary’ as no airline can reasonably be expected to have spare aircraft and crew available at every single one of its outstations. Where it gets questionable is when they try to claim future sectors as well (e.g. if on arrival back at LHR your aircraft had been scheduled to go out again to HAM as at that point it could have been swapped for another).

indeed unlucky. BA972 cancelled. I’m grateful BA protected my return as it was a steal but on the way to T2 LHR now to fly with eurowings!

• Jamie Merrill

18 JULY 2018 • 8:55PMBritish Airways passengers reported long delays and cancellations on Wednesday night after the airline reported an issue with its computer systems.

Passengers said that planes operated by the airline were not taking off from Heathrow, amid reports on social media of delayed aircraft across Europe. British Airways customers arriving at Heathrow Terminal Five were reportedly told that a computer system failure had halted all British Airways flights.

They were reportedly advised to book overnight accommodation or seek alternative travel arrangements. There were also reports that the airline online-check in service had failed. “We are experiencing disruption to our flights as a result of an issue with some of our IT systems,” British Airways tweeted earlier last night

It added: “We are working hard to urgently resolve the matter and are sorry for the disruption to some customers’ travel plans. A spokesperson for Heathrow, said: “We are aware that British Airways is currently experiencing an issue which is impacting their ability to provide boarding passes to some passengers. We will be working with the airline to support their efforts to resolve the issue as quickly as possible.”

The IT system failure comes just over a year after a computer meltdown saw the airline forced to cancel 726 flights over three days, leaving 75,000 passengers stranded and costing the company around £100m

The delays yesterday came after an earlier fire alert at Heathrow’s air traffic control tower briefly forced flight to be diverted to other airports. It "impacted operation of the airfield for a short while" on Wednesday afternoon, according to the airport.

Last May's IT failure, which also came at the start of a busy holiday period, sparked intense criticism of the company and its management, as well as frustration over the lack of information handed out to customers by BA staff. It was blamed by the company on an electrical technician employed by an outside supplier for shutting down an “uninterruptible power supply” located in the plant room of the firm's London data centre.

British Airways said in a statement: "As with a number of airlines we are experiencing some disruption at Heathrow a result of an issue with a supplier IT system.

"We are working with our supplier to resolve the matter and are sorry for the disruption to our customers’ travel plans."

It was mentioned elsewhere that other ALTEA customers were also experiencing issues so that could equally be the angle taken. That said, there’s lots of evidence that just because it’s an outsourced service doesn’t mean it’s extraordinary or indeed outside the airlines control.

Indeed, if your company has outsourced their payroll would you get a tough luck message if you were not paid?