The story in question in this thread dates from May last year - the main files on the case are in the National Archives. The files which the police were arguing should be protected give the names of informants at the time - descendants of whom may well be alive today. The principle appears to be that, given the band of nutcases for whom the Ripper saga is an all-consuming passion, descendants of informants in this case - or any other case - should not be made available.

Metropolitan Police web page on the case