The Crown Prosecution Service has been fined £200,000 by watchdogs after videos of police interviews with tearful sex abuse victims were stolen in a burglary.
One of the cases involved a "high-profile individual" - thought to refer to Jimmy Savile's former chauffeur Ray Teret, who was jailed last year for sex offences.
In all, "graphic and distressing" interviews with 43 victims and witnesses linked to 31 police investigations were on three laptops taken in the break-in.
If police had not caught the burglars and recovered the laptops then accusers may have faced reprisal, the Information Commissioner's Office (ICO) said.
Lawyers for victims said the data breach had caused a "great deal of upset and uncertainty" to vulnerable victims.
The watchdog has now fined the Crown Prosecution Service (CPS) £200,000 for the security breach.
The videos were being edited for the CPS by Swan Films, a Manchester-based company, so they could be used in criminal proceedings, when they were stolen from a flat used by the firm as a studio.
The laptops, which were left on a desk, were password-protected but not encrypted and the studio had no alarm and insufficient security, according to the ICO.
Victims of sexual offences and vulnerable witnesses are routinely filmed on video as they are interviewed by police officers taking witness statements.
Hours of interviews are edited and, with the agreement of the prosecution and defence, the edited versions are played to juries and form part of the evidence in trials - although the identities of victims must not be made public.
Still traumatised victims of Teret, 74, came forward to police with their identities protected to give evidence about his sexual abuse when they were youngsters.
The DJ and radio presenter followed his mentor Savile around "like a shadow" using his celebrity status to prey on schoolgirls and young women, with one victim aged just 13.
The women gave distressing and highly personal accounts of the abuse and, as victims of sexual offences, their identities must be kept secret by law.
Teret was jailed for 25 years last December after being convicted of seven counts of rape and 11 counts of indecent assault during the 1960s and 1970s.
The police recovered the stolen laptops eight days after they were taken in the burglary at Swan Films in Rusholme, south Manchester, in September last year.
The ICO said that, as far as it was aware, they had not been accessed by anyone else.
But the watchdog ruled that the CPS was negligent when it failed to ensure the videos were kept safe.
ICO head of enforcement Stephen Eckersley said: "The CPS was aware of the graphic and distressing nature of the personal data contained in the videos, but was complacent in protecting that information.
"If this information had been misused or disclosed to others then the consequences could have resulted in acts of reprisal."
Richard Scorer, head of the abuse team at law firm Slater and Gordon, who is representing a number of those affected, said: "It takes a tremendous amount of courage for victims of sexual abuse to report it in the first place and one of the most important factors in encouraging people to come forward is that promise of confidentiality.
"This data breach was also a breach of the trust that these victims had placed in the CPS to keep this private and sensitive information about their cases secure.
"Although it does not appear that the material contained on the laptops was accessed by anyone in the eight days before they were found, the theft caused a great deal of upset and uncertainty to victims who were already very vulnerable."
A CPS spokesman said: "It is a matter of real regret that sensitive information was not held more securely by our external contractor, and that we, as an organisation, failed to ensure that it was."
The CPS contract with Swan Films was immediately terminated.
Greater Manchester Police said no further action was taken against one person arrested for burglary and five others arrested for handling stolen goods, due to lack of evidence to prosecute.