The accident, in December 1991, occurred when a Portsmouth to Cardiff Sprinter train smashed into the back of an InterCity Paddington to Cardiff service towards the Welsh end of the four-mile tunnel. The Sprinter driver and five passengers were seriously hurt and a further 180 passengers received minor injuries.
Robin Seymour, who investigated the accident for the Health and Safety Executive, was unable to ascertain whether the crash was caused by a once-off signalling fault or by driver error. The possibility of driver error again raises the question of whether trains should be fitted with Automatic Train Protection which prevents trains going through a red signal, as recommended by the Hidden report into the 1988 Clapham Junction crash. BR would only say yesterday that the equipment was being tested on the Great Western line and 'could be considered for extension through the tunnel'.