The Independent Police Complaints Comission (IPCC) has published a report highlighting failings in the working practices of the Southwark Sapphire Unit - a police department dedicated to investigating serious sexual violence.
It found that officers there wrote off allegations as "no crimes", so they could reduce the number of unsolved cases on their books and meet official crime detection targets.
Ronke Phillips reports.
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The campaigners have raised concerns about former undercover officers being granted anonymity during the proceedings.
The Discovery School in Newcastle has said there was "no excuse" for the serious error.
The 21-year-old victim was attacked on Tuesday night.