Together TBMs Florence and Cecilia have dug a combined total of over 3.6 miles to the 78m deep ventilation shaft at Chalfont St Peter – the first of five that will provide ventilation and emergency access to the ten-mile-long twin tunnels.

The TBMs launched in May and June last year are expected to break out at the north portal in around two and a half years.

Operated by, Align – a Bouygues, Sir Robert McAlpine, and VolkerFitzpatrick JV, a crew of 17 people on board each machine keep them running, working in shifts and supported by over 100 people on the surface.

Align Project Director, Daniel Altier, said: “Florence and Cecilia reaching our first shaft at Chalfont St Peter is a great achievement for not only the tunnelling team but also construction team involved in excavating and preparing the shaft.

“In particular I would like to pay credit to KVJV and Keltbray our supply chain partners, who have been working tirelessly over the last few months to ensure the shaft is ready for the arrival of Florence and Cecilia.”

In total there will be 10 TBMs on the HS2 project – working to create 64 miles of tunnel between London and the West Midlands including major tunnels on the approach to London and Birmingham. Three machines have been launched so far.