Whenever she's out in public, the Queen carries a large and expensive looking handbag. It's invariably perfectly matched to her outfit, and we imagine she had hundreds. Nobody knows for sure what she keeps in there; it could be simply her phone, some tissues and some mints, or it could be a copy of Hello Magazine and a handgun, but the bag serves a more important purpose than just carrying her valuables.
The Queen will use the position of her bag to communicate with her staff. It would be very impolite for the Queen to directly tell someone she didn't want to speak to them anymore, and so she sometimes needs her staff to step in. If her bag is on her left arm, she's happy where she is. If she moves it to the right, she'd like to be moved on from the conversation. If she puts it on the floor, she's feeling deeply uncomfortable and requires rescue from a conversation immediately.