In March and April 2023, PC Andrew Gilligan sent inappropriate Twitter messages to three members of the public.
The messages left all three recipients disturbed enough to report his conduct to their local police forces independently of one another other.
To a lady in her seventies and a woman with autism he sent highly sexualised messages including graphic images of intimate body parts, a misconduct report states.
Neither woman had solicited the images or sexual content.
Then after becoming aware of a girl aged under 18 who had ambitions to join the police force PC Gilligan continued to bombard her with messages including the suggestion she was cute and a request to be added to her Snapchat.
On February 27 a misconduct hearing found PC Gilligan had acted without self-control and failed to treat the public with respect.
A misconduct panel said it was notable that each of the three recipients of his messages had vulnerabilities either due to old age, young age or due to having autism.
PC Gilligan resigned from the Met Police days before the misconduct hearing, which decided he should be added to the barred policing list.
PC Gilligan did not attend the misconduct hearing.
Assistant Commissioner Rachel Williams said: “The public could not have confidence in FPC Gilligan to treat them with courtesy and respect. Nor would they have confidence in the Metropolitan Police Service if it appeared not to take such behaviour.”