The fee, to be introduced from November 1, is designed to switch bookings towards BA’s NDC (New Distribution Capability) and other direct channels. It will be levied per fare component.

Agents were quick to make a comparison with Lufthansa, which launched a €16 GDS booking fee in September 2015.

Twickenham-based WOT Travel owner Paul Smith said: “I don’t sell Lufthansa if I can help it and I think this new decision means you sell other airlines where you can.

“The public can be quite fickle [when it comes to extra fees], as they’re not affected in the same way we are. I have zero sympathy for BA if they lose out...”

Andrew Earle of Andrew Earle’s Holidays in Hull added: “We don’t have any problem with switch-selling BA and it goes to show the way they treat the travel trade does have an impact… If they think that’s the way forward then there’s not much the trade can do.”

Paul Wait, GTMC chief executive, disputed suggestions that GDSs were expensive: “We would like to see robust evidence from BA to prove that point when all factors such as technology development and marketing costs, revenue and average ticket price are taken into consideration,” he said.

“Over the weekend, TMCs worked tirelessly to support clients – BA customers – so to see this level of loyalty and support ignored, and even penalised, is frustrating. As a result we fear both passenger and revenue numbers will suffer.”

The fee will be collected automatically via a “Q” charge on ticketing. Travelport, which owns Galileo and Worldspan, called the charge “the equivalent of a travel agency APD”.