Mr Spudqueen and I were discussing this last night as we live in the same sort of property, two sets of terraced houses with a ginnel (or alley) in the middle. We decided that if this happened to us we would suddenly get a taste for all night bbqs, bonfires and music, and if that didn't work we'd just leave a hose on to flood the garden (luckily our gardens are lower down than the houses). And yes, it is disgusting that people live this way, but this is no excuse for taking over someones private garden, especially when it's not even your country.