My thoughts are with you pea shoot. I have suffered aswell with smashed glass and had 3 trays of 40 module onion setts stolen. We have frequent visitors who have helped themselves to cabbage, carrots etc which is annoying but not to bad.
I remember a woman used to come to the lotties on a sunday morning to pick a few runners etc and thinking nothing of it until I mentioned to one holder that I'd seen his sister picking runners when he told me he did not have a sister and this person had been helping herself for weeks. I have reinforced the locks on my shed but it's only a deterrent if they are determined they will break in and are so open about it. I hope the noise made doing it will alert some one. some on our site leave the gate open and I have had a run in with quite a few to say shut the gate even if they are on site as they don't see whats happening at the bottom end. One fellow on our site had £600 worth of generator stolen along with other bits. They had actually cut a hole in the fence. some remarked they seen two people with bolt croppers but ignored it. What a burke.I think if we catch them slow roasting over an open barbie should do the trick. I have spoken to the police and they made anote. It seems to me if they can't deal with it from their car then they can't be bothered. Anyway chin up and happy gardening.