for the snark was a boojum you see...

And what we thought was a wasp nest turns out to be an immense hive of wild bees. This doesn't help immensely, though I guess they are less aggressive than wasps. But still living directly by back gate and so quite dangerous to all visitors - probably better than a guard dog! - but also dangerous to children and passers by.
Awake a lot of the night fretting but we hope to have a solution tomorrow. It won't be pretty but there we go.