The budget airline confirmed that it was planning to add the clause to all bookings for UK flights from April 1, 2019, after the UK is currently scheduled to leave the EU.

Kenny Jacobs, Ryanair’s chief marketing officer, said the new condition would apply when the summer 2019 schedule is released later this year, but will not be included for flights in the winter 2018-19 programme.

“In that summer schedule there will be a term and condition saying ‘subject to a regulatory environment allowing this flight to take place’,” he added.

“There is not a regulatory solution yet to replace open skies. That’s why we have applied for a UK AOC (Air Operator Certificate) to make sure we can fly domestic routes in the UK if needed.

“The UK is the biggest country in the Ryanair network but if we get to the worst-case scenario and we can’t fly, then we will be looking at ultimately moving aircraft out of the UK into other European bases.”

If any flights end up being cancelled due to Brexit in 2019, Ryanair customers will receive a full refund.

Jacobs said that such a “guillotine” situation in April 2019 was looking less likely, with the UK hoping to secure a transitional deal for up to two years, which would allow the current flight arrangements to continue.

“They will find a solution but it will just take a bit longer,” he added.

“I suspect they will work it out at some point during the transition period.”

Jacobs added that Brexit had “not affected bookings” so far, and added: “Brits will continue going to Europe and Europeans will keep coming to Britain – that’s not going to change.”

Ryanair has spent the past few months dealing with the aftermath of its pilot rostering crisis over the current winter season, which has caused the cancellation of 20,000 flights.

“We have been focusing on what we need to fix,” said Jacobs. “We’ve been dealing with the fallout from the rostering – making sure we deal with rebooking, refunds and rerouting. We have also been recognising unions and increasing pay for pilots.

“Now it’s back to business as usual. We are getting back to what our customers want – low fares and really good punctuality.”

Ryanair has ambitious growth plans and is aiming to increase passenger numbers from last year’s total of 129 million to more than 200 million by 2024.