Hither Green rail crash has immediate cause broken rail
Inquiry and report
The derailment was found to be due to a broken rail at a rail joint, where a fatigue crack through the first bolt hole in a running-on rail had progressively developed and a triangular piece of rail had broken out. The sleeper at the joint had previously failed and been replaced with a shallower timber replacement. This replacement had not been well packed, was on a shallow layer of clean ballast and the rubber pad supporting the rail on the adjacent concrete sleeper was missing.After the derailment passengers commented about trains running at excessive speed, but British Rail routinely monitored this and the number of trains running in excess of the permitted speed was small and normally only by a small amount. Complaints were also received about the rough riding of Hastings line stock and another train of the same class was tested on Southern Region and Eastern Region track. Although the ride quality was better on the Eastern region track, it was not considered dangerous on Southern Region track.The speed limit for electric multiple units on the track had been raised from 75 mph (121 km/h) to 90 mph (140 km/h) in July 1967. After the derailment the line was inspected and a temporary speed restriction of  60 mph (97 km/h) imposed. The report found that Civil Engineering and Inspection Departments had permitted too low a standard of maintenance on the line and had failed to assess the implications of increasing the speed of the trains.