Clayton Tunnel

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The Clayton Tunnel is located just north of Brighton on the main line to London.

It was the site of an early form of "Automatic" signal invented by CF Whitworth. Far from being fully "automatic" in operation, this was merely a signal that was operated by the Policeman but returned to 'danger' once the train had passed, by means of a treadle. There was one of these at each end of Clayton Tunnel, and it was the failure of the Policeman to see that the signal had not returned to danger that led to the worst ever accident on that railway. Because the signal had failed to return to stop, a second train entered the tunnel and collided with the first which had stalled.