He was charged with sexual assault but the case was abandoned before trial.
But a misconduct panel has found he did grab the woman’s breasts and lied about the incident, which took place on January 16 last year.
The woman told the police the incident had left her “feeling terrible”.
When interview Thapa suggested he had “implied consent” as he said the woman had been “grinding” against her lap but the misconduct panel concluded he was not telling the truth.
“The CCTV does not show (her) behaving in the manner described by Former PC Thapa, or in the opinion of the Panel, in a manner which suggests that she was giving consent to intimate sexual contact,” the panel said.
It concluded he made up a false account to explain his behaviour.
PC Thapa would have been sacked had he not already resigned, the panel decided.
