The Seatfrog app creates a live, dynamic bidding system for first-class seats, enabling the operator to improve occupancy rates. Prices start at £5 with auctions beginning two-and-a-half hours prior to departure and closing 30 minutes before the train leaves.

The passenger simply enters a booking reference for upcoming trips into the app, which is availble for iOS and Android devices, and Seatfrog sends a notification as soon as first-class seats become available. The passenger can then bid to win an upgrade in the auction. After the auction finishes

Seatfrog sends a new ticket to the winning bidder’s device.

Last-minute upgrades will be available between Monday and Friday on selected services from London King’s Cross to Leeds, York, Newcastle and Edinburgh.