A Scotland Yard officer has been sacked for sexually assaulting a woman he met on a "marriage introductions" website.
The police watchdog attacked the 32-year-old trainee detective constable's "despicable" abuse of trust as he was dismissed for misconduct.
The married officer was based at Hounslow police station when he posed as a single man and met the woman on the internet, the Independent Police Complaints Commission said today.
Investigations were launched in January last year after the woman he assaulted informed her local police station of the incident, the watchdog said.
Rachel Cerfontyne, of the IPCC, said: "This was a despicable abuse of a trusted position, which left a vulnerable young woman traumatised.
"She was subjected to assault and violation by a police officer. The officer has rightly been dismissed."
The misconduct panel found allegations of sexual assault proven despite charges being dropped by the Crown Prosecution Service last December.
A misconduct hearing was told the officer and his victim had agreed to meet at a Tube station in south west London for a coffee during email exchanges over a couple of days.
The officer arrived in his car and drove the woman to a police section house in Brentford. When the woman expressed concern about the change of plans, he reassured her and showed her his warrant card.
"The officer was not a resident officer at the section house at the time and had no permission to take a member of the public into the building," the watchdog spokeswoman said.
"Whilst there, he sexually assaulted her."
Commander Peter Spindler, of the Metropolitan Police's directorate of professional standards, said: "This officer was the subject of some very serious allegations and the misconduct hearing, having reviewed the evidence, found that the case against him was proven.
"He abused his status as a constable for his own gratification in a most appalling way. We will not tolerate this type of behaviour, and he has therefore been dismissed from the service for gross misconduct."