Hither Green, 1967

On November 5 1967, a piece of rail broke away as a diesel electric multiple unit passed at 70mph, causing a derailment that killed 49 people.

Although the cause was a fatigue crack at a point where a sleeper had been replaced by a shallow timber one that had been poorly supported, it was realised more generally that the smaller wheels of diesel and electric locomotives and units, combined with the high unsprung weight resulting from their axle-hung traction motors, had a more punishing effect on the track than their steam counterparts.