Thank you Ann, I don't know what cat nip seed is, but I'll find out. The thought of them staying and poo-ing in their own garden kind of appeals to me.
We don't really have fences here, but trees growing through 10ft laurel. It'll be a tripod ladder job.
I suppose I should have mentioned that it's only ever been needed as a short term solution, because if their sale goes through then they are off to live in Saintes, where their new French neighbours will benefit.