Why aren't there beavers in the Lee Valley? Or wild cats in Epping Forest? Why don't storks nest on Lambeth's lampposts, cranes darken the skies of Hackney and sturgeon swim up the Thames? All were once native to Britain. All were wiped out by people. Isn't it time for their return?
If the forces of nature are to be unleashed on our barren island because wilderness is something from which we all benefit, to which we all have a right, then it's not just the overgrazed moors of Scotland, Wales and Yorkshire which should be in focus.
Roughly half of London is green space: parks, public gardens, cemeteries and the like. And of course it's quite right that some of these are cut into football pitches, that people are able to walk to their loved-ones' graves or spread their rugs for picnics. But what about the rest? Why can't we leave forests to flourish (other than cutting some paths so we can watch them do so)? Why can't we restore once native species to the capital's parks, skies and rivers?
To an extent, this is already happening. I have found corners of London with denser woodland and less obsessive management than I've seen on many a Highland estate. My sister used to live near a cemetery which has been left to grow, delivering beautiful woodland with an astounding diversity of fungi. Look out over much of London and you see forest – much more so than if you look out over Britain's intensively farmed rural counties. But there could be so much more.
Polecats are currently spreading back across the UK. Why can't they be given a helping hand into the capital? Friends I once took into the woods at my parents Perthshire home still talk with glee of how they saw the flash of a pine marten chasing squirrels. Why are Londoners denied this stunning sight? Beavers can live happily in urban rivers. Why not in London?
The Thames isn't nearly as polluted as it used to be. Do fish species which once thrived there need a hand to return? And if they did, could osprey, sea eagles and Dalmatian pelicans be supported to swoop over the river for such prey, as they once would have? I'm not an ecologist by training, and it may well be that some of these species couldn't cope with city life. But many could, and it's time to look seriously at bringing them back.
There is a problem with all of this. The richest ecosystems are often found not in parks, but on patches of untouched and ignored land: otherwise known as brownfield sights: the early stages of the cycle of disrupted land becoming rich forest are often dismissed as weed-filled scrub. And this land is often needed for housing.
So here's my final proposal: Golftoday.co.uk lists more than 70 golf course or driving ranges in London. That's a huge amount of space to poison, bulldoze, and mow the life out of for the purpose of spoiling a few good walks, before we even start to ask questions about who mostly uses the things. Just half of this vandalised landscape could contribute significantly to Londoners having both the homes and the access to wildlife they deserve. It's time to liberate this land.