HS2's 10-mile Chiltern tunnel 75% complete, firm says

One of the two Tunnel Boring Machines (TBMs) run by HS2

The company behind the HS2 high speed rail link has revealed that its longest tunnel is now 75% complete.

HS2 gave the update about the 10-mile (16km) Chiltern tunnel that runs under part of Buckinghamshire.

It said the tunnel, which is cut at a rate of about 50ft (15m) a day, had passed Little Missenden on its way to Great Missenden.

The update came as the viability of the project linking London to the Midlands and North was called into question.

Earlier in September, the government refused to guarantee the future of the rail line between Birmingham and Manchester, while on Sunday, Defence Secretary Grant Shapps said it would be "crazy" not to review plans as costs have soared.

The MP for Welwyn Hatfield told the BBC the Ukraine war and a spike in inflation meant any government would need to make "serious decisions" on affordability.

A definitive decision on HS2 could be made in the coming days.

HS2 said work in Buckinghamshire was continuing on Phase 1, which would connect London to the West Midlands.

It said two boring machines, known as Florence and Cecilia, have been excavating the Chiltern tunnel for more than two years and were now three quarters of the way through the job.

Site teams have also begun creating interior structures for five ventilation and emergency access shafts.