A multi-million pound project to enable HS2 trains to run under an existing rail line will bring immediate benefits to passengers, HS2 and Network Rail said.

More than one mile of a branch line in Buckinghamshire between Aylesbury and Princes Risborough is being realigned, including with the construction of a new bridge.

This will enable HS2 trains running between London and Birmingham to pass beneath.

HS2 services are not expected to begin until as late as 2033, but it is hoped the work will boost reliability for Chiltern Railways passengers as soon as it is finished as infrastructure on the conventional railway will be more resilient.

Patrick Cawley, a joint director for HS2 and Network Rail’s On Network Works division, told the PA news agency: “What we’re doing really is delivering benefits to passengers on the conventional railway as a consequence of HS2, which is perhaps something that may have been lost in the headlines this weekend.

“It’s a real example of us doing work today and benefiting passengers today.

“HS2 is all about passenger benefits ultimately and levelling up, so it’s an important project for us.”

He added: “It really underlines the fact that HS2 is an integral part of the national rail network.

“It passes beneath it, it joins to it, it’ll be part of the national timetable at a point in time.

“This is a great example of us having to make changes to the conventional rail network to allow HS2 to happen, but it’s bringing real benefits to passengers today.”

Asked if speculation about the future of HS2 north of Birmingham has any impact on the Buckinghamshire work, Mr Cawley responded: “No. The wider question is one for the Government but this is part of HS2 Phase 1 from London to Birmingham.

“We’ll be out on site today and it’s very much a work in progress.”

The conventional line is being closed for 10 weeks while the work takes place.

Chiltern Railways’ services are being strengthened elsewhere during this period.