A statement from the Rail Accident Investigation Branch has now been released concerning the train crash that occurred near Salisbury on Sunday 31 October.

Police were called to a tunnel near Salisbury at 6.46pm after a Great Western Railway service from Portsmouth Harbour to Bristol Temple Meads collided with a South Western Railway service from London Waterloo to Honiton.

There were no fatalities, but one of the drivers sustained injuries believed to be life-changing.

The statement said while initial evidence indicates that the driver of the SWR train applied the brakes at the red signal light, the train did not stop, possibly due to 'wheelslide'.

Andrew Hall, Deputy Chief Inspector at Rail Accident Investigation Branch, said: "From the initial evidence we have collected, we know that that the passage of the Great Western train travelling from Eastleigh across Salisbury Tunnel Junction was being protected by a red signal.

"At this junction, trains coming from Eastleigh merge with those from Basingstoke, so the South Western service coming from Basingstoke was required to stop at that signal.

"Unfortunately, it did not stop and struck the side of the Great Western train at an angle such that both trains derailed and ran alongside each other into the tunnel just beyond the junction.

"Initial evidence indicates that the South Western train driver applied the brakes as it approached the junction and the red signal, but the train was unable to stop before passing the signal.

"This evidence suggests that the most likely cause of this was wheelslide, almost certainly a result of low adhesion between the wheels and the track. We are continuing to pursue this as a line of investigation amongst others."

Network Rail responded to the statement, saying such incidents are 'incredibly rare'.

Martin Frobisher, Network Rail's safety and engineering director, said: "Sunday's accident was incredibly frightening for everyone involved and our thoughts are with everyone injured or affected in any way.

"Initial findings suggest that low adhesion played a key part in causing the collision. It's an issue that affects railways across the world and is something that we, and our train operator colleagues, work hard to combat – so that we can run trains safely and reliably throughout autumn, and why incidents such as the one in Salisbury at the weekend are incredibly rare.

"We will continue to work closely with investigators to understand what happened and what more we can do to help prevent this happening again."