At around 12:27 on 26 June 2025, the front bogie of an out-of-service London Northwestern Railway passenger train derailed at Denbigh Hall South Junction on the West Coast Main Line. The derailment occurred on a switch diamond crossing at approximately 15 mph (24 km/h) as the train travelled north on the up slow line shortly after leaving Bletchley station. There were no reported injuries to the four members of staff on the train, however some lines through the junction remained out of use until 16:05 on 29 June 2025 for train recovery and infrastructure repair.

The train had earlier encountered a technical problem, while forming a southbound passenger service, making it unable to depart southwards from platform 4 at Bletchley. However, it was operational if driven northwards from the opposite end, allowing it to be moved away from the platform. A failed on-track machine had been stabled earlier that day on the only signalled route from the north end of platform 4, so staff at Rugby Rail Operating Centre decided to allow the train to travel in the wrong direction on the up (southbound) slow line. This wrong direction movement required the signaller to instruct the driver to pass the north end platform signal at danger and travel to Denbigh Hall South Junction without the protection normally afforded by the signalling interlocking. The intention was the train would then cross onto the down slow line at the junction and return it to normal signal control for its onward journey northwards to Kings Heath depot near Northampton.

Our investigation will determine the sequence of events which led to the derailment and will include consideration of:

• the actions of those involved and any factors that may have influenced them
• how out of course movements are determined and validated
• the management of the staff involved in the accident, including the preparation through training and assessment of those undertaking such movements
• any relevant underlying factors which might have contributed to the derailment.

Our investigation is independent of any investigation by the railway industry or by the industry’s regulator, the Office of Rail and Road.

We will publish our findings, including any recommendations to improve safety, at the conclusion of our investigation. This report will be available on our website. You can subscribe to automated emails notifying you when we publish our reports.