Ben Nedham went missing on July 24, 1991, while on holidays with his mother and grandparents in the Greek island of Kos.
There have been a number of unconfirmed sightings over the years, and several theories exist about what might have happened to the toddler, who would be 25 now if he were still alive.
The case was a high profile one both in Greece and the UK at the time, and it has featured in a number of TV programs about missing people in both countries.
A number of new potential leads have recently emerged, however, with one TV viewer in Greece contacting police to say that he thinks he resembles the pictures shown on TV of Ben aged 25.
South Yorkshire Police were unable to confirm this line of inquiry today.