Agents were forced to sort out bookings at a moment’s notice following government rule changes on travel to Spain, leaving many with deflated hopes for the rest of summer.

The trade criticised the timing and logic of quarantine restrictions and Foreign Office advice against non-essential travel to the UK’s biggest market.

Agents, many of whom rushed to contact customers on holiday and due to travel as news broke on Saturday evening, said clients were now reassessing all overseas trips this summer and autumn.

Simon Morgan, chief executive of Tailor Made Travel, said: “It came as a big surprise, with the worst timing.

“We’ve had to readminister hundreds of bookings, in some cases for the third or fourth time.

“Our staff are still smiling but they’re having a tough time. My eternal optimism is waning.”

Amanda Matthews, managing director of Designer Travel, said all clients were informed by 9pm that evening. “We hope the extra work will be remembered,” she said. “There is no logic behind the decisions which are being made very quickly, and that’s what is making us deflated.”

Premier Travel had a team working on Sunday to contact overseas clients and those about to travel, and said the impact was more wide-reaching than Spain.

Director Paul Waters said: “We’ve received calls from a big number of clients with future bookings to varying destinations and dates of travel asking ‘what if’ questions. This has put another dent in customer confidence for summer 2020, just as momentum was starting to build.”

Haslemere Travel owner Gemma Antrobus agreed: “I’ve had clients due to pay September balances rebooking for next year. It’s frustrating.”

Pole Travel director Jill Waite travelled back from Ibiza on Saturday to hear holidaymakers returning hours later faced quarantine.

“Last week we were upbeat,” she said. “People wanted to book. Now you think ‘is it worth booking at all?’

Bailey’s Travel owner Chris Bailey warned agents were now concerned about “getting to Christmas and still being able to pay the bills”.