Posted: 27/05/2014 at 10:35
When we moved in we had a massive overgrown and unloved privet hedge as well Topcat. We gave it a really, really hard prune, it did look very brown and sticky for that winter, but it soon started growing in the spring. This year it looks even better. I think you wouldn't have to wait long for it to fill out, they are fast growing. I am sure as Dove says if you explain to your neighbour why you want to trim the top they wouldn't mind. Give it a go!