You may have noticed a petition doing the rounds to open up London’s disused underground railways (we’ve certainly been tweeting it like mad). It might surprise you to learn that there are no less than twenty-six disused stations underneath London: that’s a whole lotta disused space for a cramped city. (Who’s betting you’ll grumble about this fact the next time you’re crushed to within an inch of your life on a busy tube platform).

But, encouragingly, there are some plans in the pipeline (very weak, I know) to take on some of these disused railways. These are the Rail Mail tunnels. Originally a pneumatic railway (for those of you who, like me, didn’t know, pneumatic basically means propelling things around with compressed air), the tunnels were used to whiz around post for the Royal Mail. Unfortunately the rail was closed in 2002, after the Mail announced it was making some rather gigantic losses of £1.2m a day.

Since then, the tunnels have remained empty, apart from a group of subterranean obsessives who broke into the tunnels in 2000… and posted the photos on the web.

But now their future may be on the up! (The tunnels, not the subterranean obsessives) London High Line disused space architecture competition, inspired by the success of the New York High Line competition, announced it’s winner last month. And it was… A mushroom garden! Yep, that’s right. Now, before you start quipping about how that isn’t architecture, that’s just damp and neglect, just hear me out.

Fletcher Priest architects beat a number of spanking great ideas from lido canals to bus stop roof gardens. There would be Perspex mushrooms at street level to let in the sunlight for what we all know from biology is photosynthesis. We the public would be able to traverse the tunnels, admiring the various fungi.

Which do you think should have won? And do we think it will ever be realised?