The rising number of women who allege they are raped while drunk is forcing Scotland Yard to reassess the way it investigates sexual offences in an effort to tackle the plummeting conviction rate in rape cases.

Increasing numbers of young women are coming forward to the police to say they believe they have been raped but cannot remember what happened as a result of being intoxicated, according to senior officers who have carried out a review of rape allegations made over two months in London.