Yep, the 3rd pic and the last 2 look like 'greenlaning' to me. The others must have been taken at a dedicated off-road site or an open day at a quarry.
'Green Lanes' are simply public roads in the UK that the tarmac machine missed in the 1930s when most of the roads out in the country were made suitable for cars.
Many are very, very old routes going back 2000 (or sometimes more) years. Some such as the Peddar's Way and The Ridgeway (probably the two best-known) were once huge, long-distance routes but have been lopped about over the centuries so that only about 5% of the ancient network has vehicle access by law. This is where all the conflict with off-roaders and 4x4 users comes from in the UK.
Green Lanes are wierd- only 4x4s can drive on them, simply because they're muddy and bumpy, but they're classified as any other road- some appear in street atlases and your car needs to be taxed / MOT'd/ insured to legally drive them.