Chiltern Railways has blamed a half-year loss to 30 June of £2.4m on last July's tunnel collapse at the Tesco development at Gerrards Cross.

The John Laing company said: “Tesco has accepted liability and we have now commenced a formal dispute resolution process in order to settle on the quantum of compensation.”

Adrian Ewer, chief executive of John Laing, added that the company was seeking a “significant sum” from Tesco.