Investigation Reveals Training Gaps Behind Denbigh Hall Junction Derailment

A rail investigation has found that a derailment on the West Coast Main Line near Milton Keynes was caused by a train being routed over points that were not correctly set for its direction of travel.

The incident occurred at around 12:27 on 26 June 2025 at Denbigh Hall South Junction, between Bletchley and Milton Keynes Central. An out-of-service passenger train, travelling at approximately 15mph, left the track shortly after departing Bletchley en route to a depot in Northampton. Four crew members were on board, but no injuries were reported, although both the train and infrastructure sustained damage.

According to findings from the Rail Accident Investigation Branch, the train was undertaking a wrong-direction movement due to a fault that prevented it being driven from one end. Signalling staff at Rugby Signalling Control Centre arranged a route for the movement, but this path was later found to be invalid.

The derailment happened when the train passed over switch diamond points that were set in an unsafe position for the direction of travel. Checks carried out by signalling staff failed to identify the error, and those in the leading cab did not detect the incorrect alignment before the train reached the junction.

Investigators identified gaps in staff understanding as a key factor. Knowledge of how switch diamond points function, and how trains should traverse them, was found to be inconsistent among those involved. Training for signallers dealing with movements past signals at danger and wrong-direction running was also highlighted as insufficient in some areas.

The report further noted that existing Rule Book guidance did not fully cover the specific circumstances encountered during the incident. As a result, the signaller inadvertently authorised the train to pass a signal at danger in a way that did not comply with established procedures.

Four recommendations have been issued following the investigation. These include calls for Network Rail to improve training on planning and verifying train movements during unusual operating conditions, and for both Network Rail and West Midlands Trains to enhance staff understanding of switch diamond points. A further recommendation has been directed to the Rail Safety and Standards Board to review whether Rule Book guidance should be updated to better reflect such scenarios.

In addition to the formal recommendations, investigators highlighted several learning points. These included the importance of staff recognising how personal factors may affect performance, taking time to double-check decisions, and seeking verification from colleagues where possible. Drivers were also reminded that during wrong-direction movements, reducing speed below the typical 15mph limit can provide additional time to confirm that points and crossings are correctly set.

Image: RAIB