[3] The first high-speed railway line to be built in the United Kingdom was High Speed 1 (HS1), the route connecting London to the Channel Tunnel, which opened 2003−2007.

It would then head eastwards across Kent using the existing upgraded South Eastern Main Line via Tonbridge to join HS1 at a junction at Ashford International.

[11][12][2] It would cost £10 billion to build and around 40% of the route would reuse existing tracks; the proposals included upgrades at Ashford International and Tonbridge stations.

Fast connections between the airports and Birmingham, Manchester and Cardiff were also proposed, and the proponents of the scheme claimed that it would alleviate pressure on transport within London by reducing the need for air passengers to travel through the city.

[14] Expedition Engineering's proposals were submitted to the Department for Transport (DfT) at the end of July 2018, as part of the Government's plans to encourage private investment.