Are you really going to get up and go and look for it even if you know where it is? If you really want to know, then you already know someone who can tell you (disallowing winding them up).

What's wrong with keeping information like this 'secret'?

It's no different to people keeping schtum about where extremely rare orchids are, or extremely rare birds are nesting, etc etc. Do you think that sort of information should be common knowledge too?

I've already offered to be your guide.