Tricky one.

Ask yourself...if you had been driving a car, whose fault would it be? Your answer whould be the same. He was in a parked position, and had the responsibility to ensure that it was safe to proceed before doing so. However, you were overtaking traffic at the time. You have a responsibility to ensure that it is safe to do so. This is an interesting issue - I would expect that only the traffic that you are overtaking and the oncoming traffic should play into that decision, and that the fact that he was parked and stationary should be the deciding factor. It is reasonable for anyone in the London area to expect that bicycles and motor-bicycles could be overtaking stationary traffic at a light.

If you were indeed travelling very fast, and he was proceeding with caution, then I would expect the point of impact to be on his front wing.

I have a question...did you have any injuries? I would be surprised if you didn't. See a doctor anyway.

Another way to look at it...Did you get the details of the other car that flashed him out? Did that driver state that he had flashed him?

Firstly, that driver took some responsibility if he did by flashing when it was clearly not safe to proceed. Secondly, if the driver that you hit stated that he moved because of the other car flashing him, then he is basically admitting fault. Flashing your lights or beeping your horn (in the UK) only have _one_ purpose. "To inform another road user of your presence" (paraphrased - check your highway code). They do _not_ have any meaning such as "It is safe to proceed", and if the other driver interpreted it as such and neglected to make his own observations...

But it's a mess. IANAL. I suggest you speak to one though.