100 mph sign, 1964
©National Railway Museum/ Science & Society Picture Library
Workers putting up a 100 miles per hour restriction sign on the East Coast Main Line, 9 June 1964. Before this time 100 mph signs had not been necessary as locomotives could not travel at such fast speeds. However, steam traction was being phased out at this time and was being replaced by diesel and electric locomotives which were more powerful and were capable of much faster speeds.