Most people, especially ones as arrogant as him, would hardly have driven on if you really had wronged them. These people have dual standards and expect to do un to others, that which they will not accept done to them. They are the sorts of people I could happily “Smack in the mouth”

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I have to ask whether you had any way of verifying his details (Did you see his license?), as his behaviour suggests he has something to hide (Stolen car, no insurance, banned driver – sorry if that sounds full of doom and gloom). It may be worth finding out if there is any CCTV of the roundabout.
I have to say that as the driver of classic cars (I have no “Modern”) and also a keen cyclist (By cyclist, I don’t mean someone who rides on pavements or at night without lights – these are the equivalent of the uninsured, no MOT, banned motorists), I find certain parallels exist between the two pursuits. I think that these are based on assumptions, made by the non cyclist or non classic driver, based upon their own standards.
For example, “I can only ride a bike at 10mph, so every bike travels at no more than 10mph” or “My cars are all a bit clapped after five years in my ownership, so one that is 40 years old must be on its last legs”. In each case it leads people to assume that the old car or bike is travelling much more slowly than it really is and it leads them into making inappropriate manoeuvres, such as attempting to overtake a cyclist and then turning left into the cyclist or pulling out of a junction in front of you because they assume they have plenty of time.
Of my cars, the Morris Traveller attracts more attention than either of the MGs (Midget and BGT V8 ). It was not something I anticipated when I bought it and so when (After about twenty minutes of ownership) I found an Australian tourist filming it at a motorway service station, I was taken aback. I don’t think it has been filmed since but it does tend to attract attention. The point is however that for every person who admires it, when stationary, there are ten who either can’t wait to overtake it or who appear to resent being overtaken by it.
I hope you get it sorted and that it doesn't happen again.