Cycling YouTuber and vigilante Michael van Erp told Newsflare: "I encountered these two suspected mobile phone thieves on Chiswick Roundabout, and they were clearly looking to avoid the police cars which were travelling around the area.

"They then recognised me, realised I was videoing, slowed down to talk to me and video me, and also threw a bag over the bridge onto the South Acton railway tracks.

"When they left, I called 999 and described what had happened to the police. I then went and found the bag on the railway tracks, and called the police back and told them.

"They sent a car out, and I showed them the stolen bag. The police told me that they had been chasing these thieves for most of the afternoon, and that they had gone to Chiswick House and broken car windows in the car park there to steal car contents."

I encountered these two suspected mobile phone thieves on Chiswick Roundabout, and they were clearly looking to avoid the police cars which were travelling around the area. They then recognised me, realised I was videoing, slowed down to talk to me and video me, and also threw a bag over the bridge onto the South Acton railway tracks. When they left, I called 999 and described what had happened to the police. I then went and found the bag on the railway tracks, and called the police back and told them. They sent a car out, and I showed them the stolen bag. The police told me that they had been chasing these thieves for most of the afternoon, and that they had gone to Chiswick House and broken car windows in the car park there to steal car contents.