A child had to be rescued from the tracks at a Tube station - seconds before a train arrived - after a gust of wind blew a buggy off the platform.
CCTV shows the child in a pushchair being left at the foot of the stairs of two train platforms at Goodge Street.
The wind pushed the buggy on to the tracks but the mother climbed down to retrieve the child seconds before the London Underground train pulled in.
Police said they wanted to trace the parents to make sure everyone was OK.
The pushchair was blown on to the Northern Line tracks just before 19:30 BST on 23 July, but the footage has just been released by the British Transport Police.
Ch Insp Mark Lawrie said: "This was a frightening incident, not just for the scale of the danger the child was exposed to, but also because the woman then put her own life on the line by going on to the tracks.
"We urgently need to identify the people involved to ensure the child wasn't injured as a result of the fall on to the tracks."