Ive been thinking about this some more. When the lady got out the passenger seat she said ' he thought you were overtaking and so he braked'
On reflection I had braked enough to get back in, I think he actually panicked and breaked far too much. After I hit his car we stopped within about 2 seconds so must have been doing about 15-20mph maximum.
I have tyre marks on the side of my front bumper from his rear wheel, if we were going any faster then he would have span.
The guy literally crapped himself and slammed the brakes on. I wasn't going much faster than him when i was 'tucking in' the fact i was braking and he was still getting closer was cause he was braking.
Wonder if the disabled badge was anything. He looked physically able to me.