In the same way that challenger banks have come along to re-invent legacy banking software from the ground up, Duffel is doing the same in the travel market, linking up airlines directly with travel agents with a modern platform.

Duffel's system connects with airlines’ booking channels more extensively than those of incumbent operators, like Amadeus and Sabre, meaning it can facilitate selling not just seats on a plane, but also other products such as speedy boarding, airport transfer and seat selection.

Add-on products make up an increasing part of airline revenues but are mostly sold through airlines' own websites at the moment. Duffel's technology will make it easier for airlines to sell more of these ancillary services, which is what makes its product so attractive to airline customers.