Cycling accident

While I was riding down Cannon Street just by the railway station on my way home from work last night the cyclist in front of me was knocked off his bike. I had tried to over-take him a few moments earlier but he was just a yard ahead of me when a pedestrian stepped out onto the road. Because I was so close I realised very quickly there was going to be an accident because the pedestrian had his back turned to the flow of traffic and at the last momet turned and walked into the bike. The cyclist for his part wasn't going so fast and wasn't being careless but I think he should have been shouting a loud / clear warning to the pedestrian but didn't until it was too late. As the bike stopped with the collision he went over his handlebars and he landed heavily on his back/head. I then realised he was not wearing a helmet and he lay there in front of me motionless. I had stopped but was just stood there frozen looking at him on the ground and could hear the panic in the voice of the pedestrian as he repeatedly said "I'm sorry... I'm sorry".
It seemed like a long time but it probably wasn't that he lay there on the road next to the stationary black cab. His eyes were open and slowly he started to move. Firstly he sat up and then he stood up although he was slow and lethargic in his movement. But actually he then mounted his bike and started to cycle off.
It was strange because he never spoke a word to the pedestrian. The pedestrian had made a potentially life threatening mistake and just walked away to catch his train home. The incident was over and I continued on my journey. I tried not to think about it as I needed to concentrate on my own safety for the remaining 45 minutes.
I was unusually keen to go to the running club last night and I really 'enjoyed' the training because life is good and although accidents do happen in this instance I was a spectator and the cyclist was 'okay' - well I think he was.
Lessons learnt - shout early, loud and often; be very careful when near train stations because commuters don't concentrate on traffic; and always wear a helmet.