Thurston will step down from his £620,000-a-year role as the project approaches peak construction.

He said: “The next 18-24 months will see the project move into an exciting new stage. I have agreed with the Board that someone else should lead the organisation and programme through what will be another defining period for HS2.”

Thurston joined HS2 in March 2017 from consultant CH2M where he ran the European business and worked on Crossrail.

Mark Harper, Secretary of State for Transport, said: “I’d like to thank Mark Thurston for his work over the last six years progressing Britain’s most transformative rail project. As well as successfully overseeing the start of construction, he has ensured HS2 has created tens of thousands of skilled jobs and apprenticeships across the country.

“As HS2 enters its next phase, the Government remains committed to unlocking all the benefits of this flagship infrastructure scheme – increasing rail capacity, connecting communities and growing the economy.”

Construction of the first phase of HS2 is now at its height, with major works taking place at over 350 sites between London and the West Midlands.

Sir Jon Thompson, Chairman of HS2 Ltd, said: “Mark’s leadership has been critical to the success of the HS2 programme. In his time as CEO the project has moved from a scheme in development to a major construction project that employs 28,500 people across the country.

“His legacy is building the foundations of HS2 which will bring growth and prosperity to towns and cities across the Midlands and the North. I want to thank him for his leadership and service.”

Thurston will leave HS2 Ltd at the end of September when Sir Jon will become Executive Chairman for an interim period while a new Chief Executive is recruited.