I get this all the time. Now wonder several police forces are running a campaign against close passing and other infractions, some are also accepting video evidence.
Some people simply don't want to share the road with cyclists, and think they can invent their own rules of the road. I had one the other week do the very thing you describe here, it was a taxi, who wouldn't stay behind - as required - because the road was narrow, uneven, had recently been surfaced with chippings, was damp and had several junctions. Oh, and I was approaching a blind bend.
Yep, just like your experience, I had the tail-gating, the dirty looks and in my case being force off the road to make an emergency stop by someone using their car as a weapon.
Some people need to be prosecuted before they kill. It goes way beyond simple mistakes everyone can make and they only understand one language: courts, and fines.
The writing is small because it's specifically designed for people who are too close. If you're not tail-gating why are you so flustered? Don't tail-gate. Sorted.
Report the fool.