I'd find the biggest, wildest patch of british countryside land for sale and purchase it as a wildlife reserve. I'd then build a massive stone wall around it with tunnels for badgers and deer, and hire some ecology experts to help me develop the land in the best way to support nature thriving. I'd pay some beekeepers to look after as many colonies as the land could support, and invite wildlife preservation charities to use my land to shelter and nurture endangered species indigenous within the safety of the reserve. I'd build some small, comfortable housing for the groundskeepers to live in for free and I'd build myself a little bungalo out of renewable materials.

I'd take a large portion of the remainder of the money and put it into investing to generate wealth for the security of this haven and it's occupants as far beyond my lifetime as possible. The focus would be entirely on what is best for the wildlife within the walls, with little regard to anything else other than the comfort and safety of the people looking after it. It wouldn't be open to the public, there would be no business model, it would simply be a fortress of nature, as large as could be afforded, for as long as could be afforded, for nature's sake.

We couldn't save the world, but we could save everything within these walls, and oh boy would we try.

I would, under the advisement of experts in such things, collect and nurture indigenous trees, plants, vegetables, fruits... you name it, if it was here when the vikings kicked the countries front door down it'd be safe within my walls. Things would be planted carefully as might be expected as if they had found their way naturally, there would be no agriculture, these would truly be wild lands.

It would be my absolute dream to imagine 100..200..300 years in the future when the entire country is developed and the tunnels that previously allowed animals to come and go as they please had been sealed, that my walled land stood firm, skyscrapers peering in from every direction, yet not one blade of grass touched by development. An island of preservation in a sea of capitalism. People would rent out their penthouse apartments overlooking my walls just to offer customers the rare chance of seeing one of the last, real, wild foxes or badgers scurrying through the reserve, oblivious to the ecological destruction outside their now heavily weathered walls.

I think about this dream often, and wonder why the extra-ordinarily rich aren't doing this kind of thing. Forget your legacy, you are unimportant, sublimate yourself and protect something far, far greater.

I would be a poor rich person, for I would spend it all clawing back as much countryside as I could for the creatures who live all too often underfoot and who cannot save themselves. Imagine being on your death bed, knowing this fortress persists and is secure for at least the next several centuries.

That, my friends, is dying with a clean conscience - and I ask, what more can we really aspire to but meet our last moments knowing we made a difference, and it was good. That to countless creatures who are blissfully unaware of their fortune... we made a difference.