Only 3% of rape allegations in London result in convictions, a study has found, prompting the capital’s victims’ commissioner to call for an end to the “excessive intrusion into personal data” demanded when a person makes an allegation.

The London rape review, conducted by the mayor’s office for policing and crime (MOPAC) and the University of West London, looked at 501 allegations of rape made across the city in April 2016.

It found that while 84% of allegations were classified as a crime by the police, in 58% of cases the victim withdrew the allegation. Only 6% of cases reached trial and 3% resulted in a conviction. The average length of time from the date of reporting to the trial outcome was 18 months.

Seven per cent of cases surveyed were perpetrated by a stranger. Almost three in five offences were alleged to have taken place in a private or domestic setting and 28% related to domestic abuse.

The London victims’ commissioner, Claire Waxman, said drastic improvements were needed in the way rape victims were treated. She called for police to be trained how to deal with trauma victims and for more funding for services from central government.

Waxman was appointed the capital’s first victim’s commissioner by the mayor of London, Sadiq Khan, in June 2017. In 2011 she won a landmark case to overturn the decision not to prosecute her stalker and in 2013 founded the campaign group Voice4Victims to work for improved legislation for victims of crime.