Sorry to hear about that experience but rest assured that the early morning users we know would not have discarded used condoms or broken bottles and certainly pick up after their dogs! And locking all the gates up nice and secure will hardly deter the al fresco fornicaters, boozers and litterbugs! I've seen park keepers doing an early morning rubbish pickup with their tongs on Hilly Fields so sad to say, I think it goes on everywhere.