LONDON (AP).- They foiled plots and cracked Nazi codes, but Britain’s spies were unable to solve the mystery of Charlie Chaplin’s birth. Although the entertainer is celebrated as one of London’s most famous sons, newly declassified files reveal that Britain’s MI5 domestic intelligence service found no records to back up Chaplin’s claim that he was born in the city on April 16, 1889. Uncertainty about Chaplin’s origins linger to this day — a mystery Chaplin himself may have helped to nurture. The previously secret file, released Friday by Britain’s National Archives, shows that MI5 investigated the silent film star in the 1950s at the request of U.S. authorities, who had long suspected him of communist sympathies. MI5 historian Christopher Andrew said the FBI’s red-hating chief, J. Edgar Hoover, privately denounced Chaplin as “one of Hollywood’s parlor Bolsheviks.” To the spies’ surprise, there was no record of the performer’s birth. “It would seem that Chaplin was either no