I'm parked up in this space in diagram 1, excuse the back of envelope job.
When I arrived there was a car and van already here, I parked next two the car so the van had ample space to get out. I didn't park next to the van because I knew the car park would fill up and I'd get blocked in. There are no marked spaces. If I'd parked next to the van I'd have blocked him in.
Then, diagram 2, another car arrives (Ca) and parks, closely followed b6 another car (Cb), the van is now blocked in. At this point the van driver gets out, stands next to my window and shouts that I have blocked him and should go and park somewhere else.
I could of parked where Cb is now parked but didn't as it's poor visibility when pulling out because the wall is six foot and you can't easily see what is coming from that direction and it's a busy road. Car Cb will be going soon as they (and I) park here daily and they pick up somebody at this time and then go (they have gone as I am typing this), the van is no longer blocked in and they are still sitting parked up in their van.
I have locked my door and am ignoring him. He intermittently beeps his horn and shouts for me to move my fucking car.
Who is being unreasonable? I could move my car now and block in car Ca but after the van drivers behaviour I'm not moving anywhere.