Ways not to lock your bike

Im thinking in particular about signs that say 'bikes will be removed'. If your bike is illegally taken by the business owner you could nail them for it, so Im guessing that it isn't illegal. I am not a lawyer, though.

If you lock your bike up on private property, the owner can cut the lock and remove it without warning. There is a van which drives around canary wharf all day removing bikes which have been attached to railings and stuff. The bikes get donated to a charity which dismantles them and sells them to raise money for bikes in the developing world. It's totally legal and there's nothing you can do about it, as long as there are signs up somewhere which say something along the lines of "bicycles attached to these railings will be removed" then the attitude of the law is "you had fair warning, tough shit".