The accident investigation concluded that the derailment was caused by a faulty set of points (number 2B) on the Down Main running line, controlled from Lambrigg ground frame.

[2] The 17:30 Virgin West Coast Pendolino West Coast Main Line InterCity service from London Euston to Glasgow Central derailed at 20:15 at a faulty set of points almost immediately after crossing the Docker Viaduct (the rear half of the train would still have been crossing the bridge whilst the front derailed at the points).

The momentum of the other vehicles caused the front of the second passenger carriage to jack-knife against the back of the first coach, eventually pushing it down the embankment and through 190 degrees, to face in the opposite direction to travel.

[5]: 158  The rescue operation was hindered by rain, darkness, and access problems caused by the narrow country lanes and muddy fields.

[2] Live BBC television coverage at 08:15 the following morning showed that although the whole train had been derailed, the rear carriage was standing nearly upright on the sleepers and ballast.

All the partially friction stir welded carriages remained structurally intact, with damage mainly confined to the crumple zones at their ends.

During his news conference at the site he said that he regarded the driver, named as Iain Black from Dumbarton,[8] as a hero, as he had attempted to stop the train and remained in his seat to ensure the safety of passengers.

Sergeant Jo Fawcett of the Cumbria Constabulary also offered thanks, saying that "There are so many people who have given up their own time to contribute in some way to dealing with the aftermath of the derailment that it would be unfair to name them for fear of missing someone out.

[16] Lambrigg ground frame, 660 yards (600 m) south-west of the accident site, controlled two crossovers, each one comprising two sets of points allowing trains to cross from one running line to the other in emergencies or during track maintenance work.

[9] RMT rail union leader Bob Crow said on BBC News that a points failure was responsible for the incident.

[17] Following the RAIB interim report, Network Rail released a statement in which its chief executive, John Armitt, described how the organisation was "devastated to conclude that the condition of the set of points at Grayrigg caused this terrible accident".

[19]Network Rail admitted it failed to carry out a scheduled visual track inspection in the area on the Sunday before the derailment.

[5] As part of the investigation by the British Transport Police, three Network Rail employees were arrested and bailed, one in July 2007 and two in November 2007.

[21] On 9 February 2009, the British Transport Police confirmed that none of the three Network Rail employees arrested in connection with the derailment would be charged following advice from the Crown Prosecution Service.

[25] On 13 January 2012, the Office of Rail Regulation announced that Network Rail was to be prosecuted under Section 3(1) of the Health and Safety at Work Act 1974 for "the company's failure to provide and implement suitable and sufficient standards, procedures, guidance, training, tools and resources for the inspection and maintenance of fixed stretcher bar points".

[27] Critical commentary appeared in the media concerning the knighthood awarded to John Armitt in the 2012 New Year Honours for services to engineering and construction.