David Higgins, Network Rail chief executive, said: “The Grayrigg derailment in 2007 resulting in the tragic death of Mrs Masson was a terrible event. Within hours it was clear that the infrastructure was at fault and we accepted responsibility, so it is right that we have been fined. Nothing we can say or do will lessen the pain felt by Mrs Masson’s family but we will make the railways safer and strive to prevent such an accident ever happening again.

“We have learnt from the accident, determined to recognise what we got wrong and put it right. An event like this affects everyone in the company, and especially those with responsibility for the track. Since the accident, much has changed in the way we plan and carry out maintenance work with new systems put in place to improve the quality and safety of our railway which is why we now have one of the safest passenger railways in Europe.”