Ok, I don't know about the UK, but here in the states you can find "ditch weed" all over, if you just look for it. It's wild marijuana and grows like, well a weed. Find some of it or the seeds if you can, plant it in the neighbors yard and wait a few weeks for it to grow. Once it's actually showing signs of being pot, call the cops and say they are growing an illegal substance. OR if you can find a few plants of ditchweed, pack up the buds into baggies and toss it into one of their cars, follow it up with a call from a PAY PHONE pretending to be a concerned citizen. Say that you saw a (car description) selling pot to grade school age kids and that you demand something be done about it. Give them the plates and wait for the fun to begin.