Maybe he just found himself in the wrong lane and rather than turn directly from the wrong lane, like most BMW or Audi drivers would do) he did the sensible, safe and legal thing?
I would recommend getting a camera (both front and rear). If what you say is true then the driver needs speaking to by the police. Some people will differ on this, but if someone did that to me I would take the lane; they have no other choice than to wait or run into you and if they do the latter it's open season as regards litigation. I never react or try to escalate because they will try to use it against you. I just let them fuck themselves up. People who drive like this deserve everything they damn well get. Hopefully they'll try this and get caught on film, complete with their fucking face. Take care.
The left hand lane was free when you made the turn so you should have been in it. The two cars from the junction opposite could easily have continued their journey in the right hand lane unimpeded. They must have thought that you were familiar with the highway code. They were wrong.
not even joking his the best