Return of the Wilderness to the UK?

[Tartar Horde]

The last time these islands could be called wilderness was during the mesolithic C8000 BP, the land was inhabited by small bands of hunter gatherers, moving seasonally between lowlands and higher ground in summer. The only way true wilderness could ever become reality is for the human population to crash so severly that the remaining numbers have no effect, or the ability to fix the infrastructure. For the broadleaf forests to grow nationwide again and all the rivers to follow their natural courses would in my opinion take 500-1000 years of growth to return the land to it's pristine pre agricultural state. I'm used to dealing in large amounts of time and this period in reality to geological time is but a blink of the eye.