A rail firm planning a rival low-fare service between London and Edinburgh has ordered trains that will provide the “highest level of comfort and service”.

FirstGroup said it has agreed a £100 million deal with Hitachi Rail for five new AT300 125mph intercity electric trains.

The four-hour service is expected to begin in autumn 2021 and will compete with the operator of the InterCity East Coast franchise – currently London North Eastern Railway – and airlines.

Average fares will be less than £25, according to FirstGroup.

Their design and branding has not been confirmed but they will include on-board catering and free Wi-Fi.

The first service of the day from London is expected to arrive in Edinburgh by 10am in a bid to attract business passengers who usually fly.

FirstGroup was granted permission by the Office of Rail and Road in April 2016 to run such a service between London and Edinburgh for 10 years.

Steve Montgomery, managing director of the company’s rail division, said: “We’re excited to announce the next step to providing our high-quality low fare service for customers linking London and Edinburgh.

“There’s a real gap in the market for truly affordable rail travel between the two capitals.

“Our plans show we are serious about competing with low-cost airlines and opening up rail travel on this key route to thousands of new passengers.

“The new trains we are introducing will provide the highest level of comfort and service, whilst being great for the environment and air quality.”

Karen Boswell, managing director of Hitachi Rail Europe, said: “Our Japanese-bullet train inspired fleet will play a vital role in supporting FirstGroup’s exciting new service.

“These trains have been designed to increase the number of seats available whilst harnessing the latest in comfort design to boost passenger experiences.

The deal includes ongoing maintenance and is being financed by Beacon Rail.