Sex crimes on railways have almost doubled in five years - but most perverts escape justice.
Passengers and staff reported 2,628 last year, an average of more than seven a day.
But there were only 402 prosecutions, a handful more than the 380 in 2014-15.
The total number of crime reports is almost twice the 1,402 recorded five years ago.
The figures cover crimes under the Sexual Offences Act ranging from rape and sex assault to groping, flashing and other indecent acts.
Of last year’s victims, a shocking 215 were children.
British Transport Police said they had expected a rise following a drive to encourage victims to report unwanted sexual behaviour.
But Andrea Simon of the End Violence Against Women Coalition warned: “It’s not enough to just encourage the reporting of sexual harassment and assaults. We need to be proactively identifying offenders and stopping them.”
Shadow transport secretary Andy McDonald said part of the problem was the Tory drive to remove guards from trains.
He added: “These figures underline how important a properly staffed railway is for passenger safety.”
Police said: “Every report won’t result in a conviction but each one helps us build an intelligence picture."
