I've been reading all of your comments and advice and I did email myself from my work email to my personal email last night. I'm actually feeling quite angry about it this morning. What they choose to do, how they live their lives etc is not my business but doing something like this at school changes things. I do care that they did this at school and now I'm left worrying what the ramifications may be for me when I actually haven't done anything wrong.
Without saying too much, my HOD is a bully. She has form for it and frequently has favourites/victims and very much operates that kind of mentality. So many staff have left because of her. I've managed to stay under her radar up til now, but I don't know which way this could go and I don't want to be either one of her victims or her favourite.
I've decided to speak to a senior member of staff that I trust implicitly and I am 100% certain that they will do nothing with the information if I don't want them too. My HOD and the Head are cut from the same cloth so I don't feel I can go to the Head.
If I'm honest, this is not about them in the cupboard anymore, this is about selfishly protecting my own interests. I know that sounds awful and some of you will be appalled but that's how I feel. They can do what the hell they like but I feel like I've been brought into it because of their actions.
I'll probably leave this thread now, I'm feeling pretty stressed and not sure I can deal with being told how awful I am, but thank you to everyone who took the time to post their thoughts.