Police have released an image of a mystery man who tried to collect a child who did not know him from school.
The apparent stranger turned up at Beulah Junior School in Thornton Heath at about 12.20pm on Monday and told teachers he was there to collect the child, whose name he knew.
But the pupil told teachers he did not recognise the man, who then left before staff could establish who he was.
Staff at the Beulah Road contacted police, who have so far been unable to establish his identity.
The child's family did not recognise the man.
Detective Constable Stephen Hall, of the Metropolitan Police, said: "This is an unusual incident, as it appears the man knew the child's name, but his family are currently unaware who he was.
"We're extremely keen to establish his identity so that we can get to the bottom of why he was there. I would ask anyone who thinks they may recognise this person to get in touch with us."
Anyone with information can contact Croydon police by calling 101 and quoting reference 154568 or calling Crimestoppers anonymously on 0800 555 111.