On 20 November 1955, at approximately 13:15, a passenger excursion train met with disaster near Milton, between Steventon and Didcot, on the Western Region of British Railways. The train, carrying passengers on a day trip from South Wales to London, derailed while negotiating a crossover, resulting in eleven fatalities and 157 injuries. The scale of the incident made it one of the more serious railway accidents of the post-war era in Britain, and it shocked both the local community and the wider public.

The train had departed Treherbert at 08:30, bound for London Paddington, and consisted of ten coaches hauled by the Britannia-class Pacific locomotive no. 70026, named Polar Star. It had been diverted from the up main line due to engineering work, requiring it to take the up goods loop instead. This loop involved a sharply curved crossover designed for low-speed movements, which the train entered at a speed far exceeding safety limits, precipitating the derailment.

When the locomotive and leading coaches left the track, they tumbled down a steep embankment, compounding the damage and casualties. The first four coaches were heavily damaged, with some carriages destroyed entirely, and several others derailed. Rescue efforts were challenging due to the wreckage, with railway staff, local emergency responders, and military personnel working quickly to free trapped passengers and administer aid.

Investigators determined that the primary cause of the derailment was the train entering the crossover at excessive speed, with driver error cited as the main factor. However, the inquiry also highlighted contributing systemic issues. These included the alignment of signals and design characteristics of the locomotive that made it more difficult for the driver to see and respond appropriately to warnings.

The railway route had originally been part of the Great Western Railway, which meant that signals were mounted on the right-hand side of the track. The Britannia-class locomotives, however, placed the driver on the left-hand side of the cab, reducing visibility of the signals. Compounding the problem, the berth track circuit approaching the crossover was considerably longer than the train itself, making it difficult for the signalman to accurately assess the train’s speed in time to intervene or provide a warning.

In the aftermath of the Milton crash, British Railways introduced a number of safety improvements to prevent similar incidents. Signalling systems were modified to implement an “Approach Release” procedure, ensuring that drivers could not see a proceed signal for a crossover until the train had slowed sufficiently. Handrails on the smoke deflectors of Britannia-class locomotives, which had been found to obstruct the driver’s view, were removed and replaced with recessed hand holds. These measures, together with lessons learned from the accident, contributed to safer operations on the railways in the decades that followed.