A cyclist in London witnessed a van driver watching what appeared to be porn on his phone while at the wheel in central London.

The extraordinary scene was captured as the cyclist, Greg, cruised along Cannon Street, heading east towards Monument and London Bridge.

He said: "As I pulled up at a red light directly adjacent London Cannon Street Train Station I noticed the driver... had also pulled up at the red light while watching a video while driving."

While the van was stopped at the red light, Greg went around the back of the van to the driver's side window.

"When looking inside the cabin from the drivers side window I could clearly see the driver watching a video. The lights soon changed green and the driver being reported continued through the green light and appeared to still be watching the video on his phone," he said.

The driver then went further up Cannon Street where they passed the exit to Bank Underground station before stopping at the next set of lights, at Monument junction. Then the cyclist got a shock.

"I pulled up alongside again on their drivers side and was able to continue to observe them watching the video. It was at this point I was able to make out the content of the video was of an adult nature and the driver was most definitely not in full control of their vehicle."

"I then noticed they took their right hand off their phone and began masturbating. The lights then changed ahead where they then continued on driving through Monument junction using their phone still. I suspect the van has an automatic transmission as he was operating the gearstick on the wrong side of the vehicle for a right hand drive vehicle as he set off," he continued.

"I was turning down onto London Bridge so I briefly pulled up alongside their driver's side window, where I could still witness them watching the video on their phone. I then turned right onto London Bridge and continued my journey where I then did not see the driver again," he concluded, with what one assumes is some relief at the end of his disturbing experience.

The cyclist says he has submitted the footage as a Police report.

While the video does appear to show adult content on the man's phone, it does not clearly show the man masturbating, though Greg is sure that is what he saw.

I was cycling along Cannon Street in a easterly direction towards Monument and London Bridge. As I pulled up at a red light directly adjacent London Cannon Street Train Station I noticed the driver being reported had also pulled up at the red light while watching a video while driving. They were stopped at the time for the red light so I went back around the rear of their vehicle and approached it again from the drivers side window. When looking inside the cabin from the drivers side window I could clearly see the driver watching a video. The lights soon changed green and the driver being reported continued through the green light and appeared to still be watching the video on his phone. They went further up Cannon St where they passed the exit to Bank Underground station. They were caught at the next set of lights at the Monument junction where the light was red. I pulled up alongside again on their drivers side and was able to continue to observe them watching the video. It was at this point I was able to make out the content of the video was of an adult nature and the driver was most definitely not in full control of their vehicle. I then noticed they took their right hand off their phone and began masturbating. The lights then changed ahead where they then continued on driving through the Monument junction using their phone still. I suspect the van has an automatic transmission as he was operating the gearstick on the wrong side of the vehicle for a right hand drive vehicle as he set off. I was turning down onto London Bridge so I briefly pulled up alongside their drivers side window where I could still witness them watching the video on their phone. I then turned right onto London Bridge and continued my journey where I then did not see the driver again.