“Can you drive safely with your mobile phone?” asks the cyclist who shot this footage. “Yes, I can,” replies the driver. To be fair to him, when he later crashes into the back of the car in front, he isn’t actually using his phone. (You can see a longer version of the video here.)

The Scotsman reports that the incident occurred on the A739 Switchback Road between Bearsden and Glasgow last month.

Dr Dave Brennan spotted a motorist using his phone at the wheel and challenged him about it.

"I called over to encourage him to stop using it, as it is not safe to drive whilst look at a phone. He later started talking to me, and during that conversation claimed he could drive safely when using his mobile phone.”

The motorist drove off, but urban traffic being urban traffic, Brennan soon caught up.

"There is often a queue of traffic on this road, so it was not unexpected for me to catch up with him. He'd complained I was previously cycling along at '3mph', so I smiled and waved as I went past, pointing out the fact he was the one now doing 3mph.

"As his window was wound up, I'm not even sure he heard me, but he probably saw me wave. He then proceeded to accelerate forward as the traffic ahead of him stopped and he crashed into the car in front. I spoke to the two drivers. I offered my footage to the driver in front as evidence, but they decided to settle it between them.”

Brennan said he didn’t think the driver was actually using the phone when he crashed.