I had a small van do similar to me at the traffic lights when I was on the BM. He found himself in the right turn only lane (tying to overtake people waiting patiently) and I was behind him going to turn right. He decided to back up to get space to get back into the other lane but didn't see me behind him. Luckily it was only at the end of his manoeuvre and he was nearly stopped, but the van still actually rode up onto my front wheel!
Luckily no damage was done.
Cheers, T i m