I've been commuting from West London to the city and back for 4 years. Last night heading home I had a unique experience... At Trafalgar square I noticed a cyclist on a racing bike, without clipless pedals. A bit rare, just barely registered it in my mind. Said cyclist proceeds to RLJ down the Mall ahead of me. I'm on my winter bike - hybrid with full mudguards rattling away. I'm taking it easy home, not going fast nor slow. When I get to Buckingham Palace I go up Constitution Hill on the cycle path, not the road. The cycle path is a slight uphill drag, dark and a tight squeeze. There is an iron fence on the left, cyclists coming down on the right and pedestrians further over to the right. Going up the path I start to catch this same cyclist. It's not safe to pass so as I get close to him I freewheel and regulate down to his speed. You'll have to trust me that I wasn't tailgaiting or wheelsucking. However, I was behind him. He was bouncing away trying to go fast. He seemed to be a bit tired. He then glances behind as he hears my mudguards and in an instant does a full emergency stop! WHAT THE F**K?! It was clearly an aggressive move toward me. Thought I was too close? Was trying to beat me up the hill or something? I wasn't too close and managed to stop. Barely. I couldn't go to the right or left of him. Then I...what would you do next?