What's Behind the Green Door?

Or is it pink? Is it a door, or a fence, or maybe even a wall?  It's pretty secure, whatever it is.  Seen down by the river in Kelso.

Our street featured in the local paper tonight. It has been measured by the Ordnance Survey and pronounced the third steepest in Scotland. So says the Southern Reporter.  Now I can feel justified in puffing and wheezing as I make my way up it. 

Thanks to Marlieske for hosting DS.