 Late in the night of 19 September, the Semi-Fast Mail train was due to call at Grantham.The signalman at Grantham south had his down signals off, but the signalman at Grantham North had all of his down signals at danger and the junction points set from down main to down branch to protect a goods train crossing from the up Nottingham line to the up main line - across the down main line on which the Mail was approaching.It was a clear night with patchy rain, as the Mail roared towards the station passing the south box.