London(CNN) An adult performer who filmed himself having a threesome in front of passengers on a London underground train has been handed a £1,000 ($1,300) fine.

George Mason, 35, had sex with his former partner Nicholas Mullan, 24, and a third man who has not been identified, while traveling on a Northern Line train on the city's Tube network.

Mason uploaded the footage onto Twitter months later, which led to him being reported and charged with outraging public decency, according to the Press Association.

"The incident is recorded by them and the video of what happened was subsequently uploaded on to Twitter, where another gay man saw it, thought that had crossed the line of what was acceptable behavior and the incident was reported to the police," prosecutor Robert Simpson said during the hearing, PA added.

An investigation found that the footage had been posted to an account that was linked to Mason.

The encounter between the three men occurred between Leicester Square and Waterloo stations, a three-minute journey which includes two stops.