In reply to UKH News:
'If they are spending the night away from the car park (not camping there) we would only expect people to pay for a day's rate.'
Good to get that in writing, cheers for asking in the first place.
Judging from this:
http://www.whatdotheyknow.com/request/enforcing_pay_and_display_parkin
It could be said that the car park may cost £10,000 a year, or 3300 day cars, or 10,000 hour parked cars before it turns profit (9 to 30 cars a day,) which seems a lot. I wonder if a freedom of information request would work with the forestry commission to see what their costs were?