RAIB: Wrong-Route Move Led to West Coast Main Line Derailment

The Rail Accident Investigation Branch made four recommendations as a result of its investigation into a derailment at Denbigh Hall South Junction, near Bletchley in Buckinghamshire, on June 26, 2025.

An out-of-service passenger train derailed on the West Coast Main Line after it ran over junction points that were set in an unsafe position for the direction it was traveling, the Rail Accident Investigation Branch said. No one was injured, but the train and railway infrastructure were damaged, RAIB said.

The derailment happened at about 12:27 p.m. on June 26, 2025, as the train passed over Denbigh Hall South Junction between Bletchley and Milton Keynes Central stations. The train, traveling at about 15 mph, started a move from Bletchley station to a depot in Northampton when it was required to make a wrong-direction movement over the junction.

RAIB said the wrong-direction movement was necessary because a fault prevented the driver from moving the train from the cab at one end. Once the need for the movement was identified and agreed, signallers at Rugby Signalling Control Centre proposed and implemented a route they did not realize was invalid, and subsequent checks did not identify the problem.

The train derailed on switch diamond points that were not correctly positioned for the movement. RAIB said no one in the train’s leading cab noticed the points were unsafe as the train arrived at the junction.

A “probable underlying factor,” RAIB said, was that staff involved had variable knowledge and understanding of switch diamond points and how trains operate over them. The agency also said a “possible underlying factor” was that signaller training on authorizing trains to pass signals at danger and conducting wrong-direction movements did not sufficiently reflect the strategies and knowledge used by experienced staff.

RAIB issued four recommendations, including additional training for signallers on route-setting tools during out-of-course events, improved knowledge and training on switch diamond points for relevant staff, and a review of whether the Rule Book should address scenarios where a signal at danger is located at or near the start of a planned wrong-direction movement.