I had a miserable commute in this morning. I was told by a van driver that I needed to learn how to ride a bike within 3 minutes of leaving home. Then this happened. I was riding along the very busy Bayswater Road quite happily. Suddenly, as I tried to accelerate after a light, my chain completely slipped and I was peddling on air. I completely lost my balance and knew I would crash. By some miracle, I managed to fall right on to the pavement and not the road (there was a taxi very close behind me) and I got away with a few grazes. It was shocking more than anything else and seems to prove to me that you should always have a well-maintained bike if you're messing around on the big roads. I suspect my chain is getting old and it's certainly making a lot of creaking.
Anyway - see what you think as I had my helmet camera on at the time.