Wendy and Will Read from Leicestershire had paid BA £319 for a three-day break to the Czech capital, departing on 26 February. Their passports expire on 13 March and 13 April respectively.

When the UK leaves the EU, the remaining members may impose a minimum-validity restriction on British travel documents. But currently UK passports are valid for anywhere in the European Union, including the Czech Republic, up to and including the date of expiry.

But when the couple tried to check in at Heathrow, says Mr Read, “We were told we would not be able to fly to Prague as our passports did not meet the expiry criteria set by the Czech authorities.”

BA staff insisted their passports needed to be valid for a minimum of 90 days from the date of return travel.

Mr Read, a retired teacher, says he and his wife were “devastated” at the prospect of losing their holiday. After the couple had been removed from the flight manifest, they asked to speak to a British Airways manager at the airport. They pointed out an official website which indicated their passports were valid for entry into the Czech Republic.

“The manager agreed there was a discrepancy, but he showed us a book that the airline uses to check entry requirements, and he was adamant that we would not be allowed entry,” said Mr Read.

The Czech Embassy in London has confirmed that the couple’s documents were valid for the proposed trip. The only stipulation is: “The travel passport has to be valid for the entire duration of stay in the Czech Republic.”

When the disappointed couple returned home they set about challenging the airline over the decision.

They found a case reported by The Independent in 2013 in which British Airways wrongly denied boarding to a student from Brighton on the same Heathrow-Prague route. On that occasion, BA swiftly paid the victim the stipulated €250 in denied-boarding compensation, reimbursed his travel expenses for the wasted journey to Heathrow and gave him a £250 voucher for a future flight.

But a week after Mr Read complained about being bounced from the Czech flight, the airline continued to blame him despite all the evidence to the contrary. A BA customer-service agent told him: “It’s your responsibility to ensure you’re carrying the correct documents.

“As you didn’t have the appropriate passport and you were denied boarding your flight, I’m afraid this means we can’t offer you a refund of your ticket.

“I know this isn’t the answer you were expecting but I hope we’ve managed to explain our position.”

After Mr Read contacted The Independent, British Airways investigated the case again and accepted it had wrongly barred the couple from the flight.

A spokesperson for BA said: “Unfortunately on this occasion our systems recommended an incorrect course of action.

Mr Read said: “It seems that they have done nothing to address the problem of their systems and staff continuing to refuse to allow UK customers flying to the EU with less than 90 days remaining on their passports, despite giving assurances that they would take action to remedy this.”

The airline is required to pay Mr and Mrs Read €250 each under European passenger-rights rules on denied boarding. It has also offered £137 to cover the cost of their wasted journey to Heathrow. After previous similar cases, BA has given vouchers to passengers it has wrongfully offloaded, but has not done so in this case