The 08:00 up Uckfield-Oxted DEMU train, 2E27 consisting of Class 205 three-car units 205018 and 205001, was crewed by driver Brian Barton and guard Jonathan Brett-Andrews.

The signal was meant to be held at danger for 2E27 to await the passage of the 08:04 Oxted-Uckfield DEMU down train 2E24, consisting of Class 205 three-car units 205029 and 205032, crewed by driver David Rees and guard R. Boyd.

Because of a lack of communication with the train crews, the Oxted signalman was unable to prevent the ensuing collision.

The reason for cancelling the contract to fit Cab Secure Radio to this line prior to the incident, as mandated in the wake of the previous Clapham disaster and Hidden report recommendations, remains unclear; however it seems likely that the changes occurring at the time, such as the channel tunnel and privatisation of the rail network, took priority over funding.

The separate-chassis construction of the elderly British Rail Class 205 stock, based on the BR Mk1 design, led to overriding of one carriage by the next.