Mason is 10. He looks out on Canary Wharf from his high-rise. He wants to take film-maker David Bond on a tour of his manor, where he takes his dog for a walk to the patch of green that is his meagre playground."People moan at us for playing ball games," he says as he heads past the forbidding signs and down the "curly wurly" stairs of his concrete jungle.
And then there it is, a patch of scrub no bigger than a saloon car. They have to sidestep the dog poo because, being the only green around, it is the sole dog toilet too. My dog loves this grass says Mason, who loves it too, although he'd love a proper play area more.
He shows Bond a building site. "There was quite a bit of greenery but they've put buildings on to it and they've taken space from us and it's not fair."
The world to Mason and his contemporaries is hard-edge and hostile and outdoors is a place of fear.
Bond, the driving force of documentary Project Wild Thing is also a Londoner. His children Ivy, five, and Albie, three, have a garden but they too are addicted to the screen.
Brain specialist Professor Susan Greenfield tells him: "Wouldn't it be an irony if the very technology that has freed us from fear and discomfort and pain is depriving us of all the things we treasure and turning us into glassy-eyed zombies?"
Bond says: "I was happiest when I was playing outdoors. My children don't do that. I can't persuade my children to go outside."
Bond's Big Idea is to become the marketing manager for Nature. If the brands can influence children's thinking, then modern techniques should be applied to the oldest of entertainments.
He dresses as a squirrel, places "No Ball" balls in Mason's concrete jungle to play "No Ball games" and hectors shoppers in the Regent Street Apple Store: "Stop buying iPads. You've got enough iPads now."
He comes up with an idea - "the ultimate playground" - and a selling point - the confidence that children gain from climbing a tree or facing a fear.
The film charts the highs and lows of his campaign as he launches apps, wins pledges and market-tests nature on children and finds them initially sceptical but then quickly receptive to the idea once they see the potential.
Bond says: "They do like my product but without branding around it, they get it or choose it."
It is perhaps the adults' bubble wrap mindset that presents the greatest obstacle. And that - spoiler alert - is the biggest epiphany of his campaign.
It's the all-pervading, statistically insignificant fear of the paedophile that has helped turn children into prisoners with consequences that include higher rates of depression, ADHD and obesity.
BBC naturalist Chris Packham tells him: "It's not the kids who don't want to put their hands in the mud or jump in the pond or pick up a worm, it's the adults that have said no."
Go to projectwildthing.com for film information and ways to get involved.
SPIRAL NOTEBOOK
Just over three miles from Greenwich Park, a bunch of Eltham Hill High School students are telling film-maker David Bond about the not-so-great outdoors.
"It's dull. Boring," says one. "I like staying home," says another.
A third says: "Nature messes your clothes and the only clothes you'd want to get messy are not those you'd wear outside."
Bond is on a mission. To get children re-connected with nature. To reverse a trend that will see the next generation have a shorter life expectancy than their parents. To instil confidence and inspire awe.
He takes the girls outside. They are lost in a field. Clueless and grumpy. Then he shows them some wild flowers, puts them in touch with a tree. They begin to see potential, begin to relax in an environment they had previously feared.
Nature is no panacea, it is not a portal to lost innocence but it does, as the film shows, return a prematurely jaded teenager to a "childlike sense of wonder".
"I used to think this was about children's tastes changing," Bond says in his documentary Project Wild Thing. "But this is about the barriers adults have put up."
A few years ago, when capitalism looked like a busted flush, there was an appetite for a less aggressive more harmonious way of life.
There was no revolution, of course. We were never going to dump the banks just like that.
But getting a child up a tree could prove a significant first step to something more meaningful.
