We live in London in a terrace house in Zone 2.
Our front fence is lower (a plain brick wall) than most houses on our street who have bricks plus railings. For some reason, in the last six months, we seem to get all sorts of people sitting on our front fence at all times of day, even really early - we are fairly regularly getting woken up by local kids chatting loudly on our front wall.
I'm very tempted to plant a hedge of pyracantha to deter our fence sitters. Is this TOO anti-social? Is there anything I need to be aware of? They grow fast, have spikes, and suit clay soil - they tick all the boxes for me.