Five year-old David Lawrence was found dead in a public lavatory in a children’s playground in Southwark, south London, in 1968.
He lived with his mother Joyce and father George in Rochester House, a block of flats on Manciple Street overlooking the playground off Tabard Street.
On the afternoon of 8 March he went shopping with an aunt before heading towards the park to play on the swings.
David was last seen alive by a neighbour at around 3.40pm.
His body was found by a park keeper later that night. Newspaper reports gave conflicting reports about his injuries, with some stating he had been stabbed five times in the back while others reported he had been suffocated or battered to death.
Scotland Yard said they were investigating the case as a murder but nobody was ever charged.
The police files relating to the case are kept at the National Archives but are not available for inspection until 2066.