The crash occurred at 18:58, and involved the 14:50 fish train from Fleetwood to London Broad Street.
When the signalman had accepted the fish train from the previous signalbox to the North, he needed to swing the facing points (that allowed entry into the Up Platform Loop from the Up line) from reverse to normal.
However, he was able to push the lever back into the frame and engage the point lock and thus clear the signal.
This accident is one of the very rare occasions where mechanical interlocking has failed to work correctly.
This event, alongside the Abbots Ripton rail accident, is the basis for the story The Flying Kipper in the Railway Series by Rev.