This can be one of the most muggle-dense places in the country on a sunny summer day. How to hide a cache that wont be discovered but can be retrieved. Hopefully I have managed this here. I think you can get away with studying the object at GZ without attracting too much attention. Even so, retrieval and replacement will be tricky when it's busy. At 7am in January it will be a doddle.
Znfg. gjb srrg bss gur tebhaq.