The Parole Board has postponed the next parole hearing for the country's longest-serving prisoner by three years, because it still considers him a high-risk sexual offender.
Alfred Vincent, 77, has 13 convictions for sexual offending but admitted abusing more than 100 children before being imprisoned 47 years ago.
Vincent accepted the decision, saying it was "all right".
In an independent assessment, he admitted to committing up to 500 offences against children aged between eight and 15.
He has also been stood down from some prison programmes for sexual activity or behaviour with younger male prisoners.
The board said Vincent's sad history suggested he may never be released but because of his age the deferral is for three years instead of the maximum five.
His lawyer, Tony Ellis, said the decision was not surprising and he believed the board was worried about the potential cost of re-integrating Vincent into society.