[Gremlin]

It may be common land for the use of the people but the people who use it don't maintain it. Someone has to look after the toilets, fill the potholes in build that nice new bridge,keep the paths tidy and pick up the rubbish the visitors leave behind. That's where the small charge goes.
I agree, it would be nice if it was free but a quid is not bad.
I hope it doesn't stop you taking photos there Dave, I enjoy looking at places I haven't walked round although I have parked there a few times with June and fed the birds and then sat with a nice ice cream.