I agree with nearly everything you have written Stephen.
I encountered several of each type today on the M6 on YOUR patch!
If I cautiously pass a middle lane hogger on the inside, can I count on your support?

I have adopted this approach when lane 3 has been very busy, and feel more effort should be made to stamp out middle lane hoggers through TV campaign, and use of "Driving without due consideration for other road users". Is that still on the statute book?
As to vehicles appearing from nowhere, I had two instances today - the first M6 northbound near Forton Services - not quite out of nowhere, but close!
An electric blue car - new Ford Focus I think, came up behind me as I passed a car in Lane 2. I was doing close to 80 mph on the speedo, when suddenly the car which had appeared in my mirror as I initiated my manouver, appeared large in my mirror, flashing his headlights, which could be barely seen, he was so close!!
I chose to pull over only when it was safe, and he sped off at speed, dissapearing into the distance within a minute or so.
His index was H 200 so he seems to have a ponchant for attention - I hope he gets it REAL soon before he has a tangle with an innocent motorist.
The second was nearly home - approaching the on ramp of the A590 onto the A591. Nobody behind me, so I pulled over and flashed my lights to allow a VW camper van loaded with bikes off the slip, onto the carriageway.
As I QUICKLY drew level, a blue Audi A4 estate appeared in my mirror, just a few feet back.
He had to have crossed the hatched lines which divide the on-ramp from the A590 to get into that position, and the VW with my encouragment had crossed at the earliest point!
Needless to say as soon as I pulled over, he dissapeared just as quickly past the Prizet junction, even though I was doing 70 mph.
Turned into Kendal, index P? 54 XCL. Hope to see him in the Gazette before long, before he forces somebody into becoming a bonnet mascot!
In each case, tailgating seemed just one aspect of their style of driving which would concern me.