halfway up a wall

The window ledge must be about 30 feet from the ground.  The walls of the shed are about 18" thick.  I assumed them to be solid, but now I'm not so sure.  This Buddleia does not appear to be growing in the soil at the base of the wall, but from a gap about halfway up.

I'm having a coffee, just chilling out, watching the birds balance on the branches - a warbler of some sort, a couple of blue tits and then a robin.  

It flies up and pecks at the window; I'm assuming it sees the ornamental  bird on the windowsill as some sort of rival.  It has about three or four attempts to scare our bird off and then gives up.  

Anniemay wanted to 'trim' the Buddeia - i.e. cut it down, but I convince her not to on Health and Safety grounds.  We can't actually open this window and so the only way would be for her to climb up the wall.  I'm not signing a risk assessment for that.  Not only that - it's not ours to cut.

So we'll just sit back and watch the show - we have the flowers and butterflies to look forward to.