Accidents are shocks to any system, and the railways are no exception. Though Britain's rail network is now among the world's safest, it has been wrought by generations of experiment and occasional tragedy, its reliability developed often in response to particular accidents that demonstrated problems or vulnerabilities. Early incidents like the felling of William Huskisson by Stephenson's Rocket in 1830 led to improvements in signalling and braking methods, and over the years rolling stock, track design and train protection systems have all improved as accident led to action. Greg Morse charts these developments through the events that highlighted their necessity, including the Armagh collision (1889), the Harrow & Wealdstone disaster (1952) and the derailment at Hither Green (1967), ending with the Clapham Junction tragedy of 1988.